diff --git a/OpenNest/Forms/SplitDrawingForm.Designer.cs b/OpenNest/Forms/SplitDrawingForm.Designer.cs
new file mode 100644
index 0000000..dc2ca13
--- /dev/null
+++ b/OpenNest/Forms/SplitDrawingForm.Designer.cs
@@ -0,0 +1,641 @@
+namespace OpenNest.Forms
+{
+    partial class SplitDrawingForm
+    {
+        /// <summary>
+        /// Required designer variable.
+        /// </summary>
+        private System.ComponentModel.IContainer components = null;
+
+        /// <summary>
+        /// Clean up any resources being used.
+        /// </summary>
+        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing && (components != null))
+            {
+                components.Dispose();
+            }
+            base.Dispose(disposing);
+        }
+
+        #region Windows Form Designer generated code
+
+        /// <summary>
+        /// Required method for Designer support - do not modify
+        /// the contents of this method with the code editor.
+        /// </summary>
+        private void InitializeComponent()
+        {
+            this.pnlSettings = new System.Windows.Forms.Panel();
+            this.pnlPreview = new System.Windows.Forms.Panel();
+            this.toolStrip = new System.Windows.Forms.ToolStrip();
+            this.btnAddLine = new System.Windows.Forms.ToolStripButton();
+            this.btnDeleteLine = new System.Windows.Forms.ToolStripButton();
+            this.statusStrip = new System.Windows.Forms.StatusStrip();
+            this.lblStatus = new System.Windows.Forms.ToolStripStatusLabel();
+            this.lblCursor = new System.Windows.Forms.ToolStripStatusLabel();
+
+            // Split Method group
+            this.grpMethod = new System.Windows.Forms.GroupBox();
+            this.radManual = new System.Windows.Forms.RadioButton();
+            this.radFitToPlate = new System.Windows.Forms.RadioButton();
+            this.radByCount = new System.Windows.Forms.RadioButton();
+
+            // Auto-fit group
+            this.grpAutoFit = new System.Windows.Forms.GroupBox();
+            this.lblPlateWidth = new System.Windows.Forms.Label();
+            this.nudPlateWidth = new System.Windows.Forms.NumericUpDown();
+            this.lblPlateHeight = new System.Windows.Forms.Label();
+            this.nudPlateHeight = new System.Windows.Forms.NumericUpDown();
+            this.lblEdgeSpacing = new System.Windows.Forms.Label();
+            this.nudEdgeSpacing = new System.Windows.Forms.NumericUpDown();
+
+            // By Count group
+            this.grpByCount = new System.Windows.Forms.GroupBox();
+            this.lblHorizontalPieces = new System.Windows.Forms.Label();
+            this.nudHorizontalPieces = new System.Windows.Forms.NumericUpDown();
+            this.lblVerticalPieces = new System.Windows.Forms.Label();
+            this.nudVerticalPieces = new System.Windows.Forms.NumericUpDown();
+
+            // Split Type group
+            this.grpType = new System.Windows.Forms.GroupBox();
+            this.radStraight = new System.Windows.Forms.RadioButton();
+            this.radTabs = new System.Windows.Forms.RadioButton();
+            this.radSpike = new System.Windows.Forms.RadioButton();
+
+            // Tab Parameters group
+            this.grpTabParams = new System.Windows.Forms.GroupBox();
+            this.lblTabWidth = new System.Windows.Forms.Label();
+            this.nudTabWidth = new System.Windows.Forms.NumericUpDown();
+            this.lblTabHeight = new System.Windows.Forms.Label();
+            this.nudTabHeight = new System.Windows.Forms.NumericUpDown();
+            this.lblTabCount = new System.Windows.Forms.Label();
+            this.nudTabCount = new System.Windows.Forms.NumericUpDown();
+
+            // Spike Parameters group
+            this.grpSpikeParams = new System.Windows.Forms.GroupBox();
+            this.lblSpikeDepth = new System.Windows.Forms.Label();
+            this.nudSpikeDepth = new System.Windows.Forms.NumericUpDown();
+            this.lblSpikeAngle = new System.Windows.Forms.Label();
+            this.nudSpikeAngle = new System.Windows.Forms.NumericUpDown();
+            this.lblSpikePairCount = new System.Windows.Forms.Label();
+            this.nudSpikePairCount = new System.Windows.Forms.NumericUpDown();
+
+            // OK/Cancel buttons
+            this.btnOK = new System.Windows.Forms.Button();
+            this.btnCancel = new System.Windows.Forms.Button();
+
+            // Begin init
+            ((System.ComponentModel.ISupportInitialize)(this.nudPlateWidth)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudPlateHeight)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudEdgeSpacing)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudHorizontalPieces)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudVerticalPieces)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudTabWidth)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudTabHeight)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudTabCount)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudSpikeDepth)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudSpikeAngle)).BeginInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudSpikePairCount)).BeginInit();
+            this.pnlSettings.SuspendLayout();
+            this.grpMethod.SuspendLayout();
+            this.grpAutoFit.SuspendLayout();
+            this.grpByCount.SuspendLayout();
+            this.grpType.SuspendLayout();
+            this.grpTabParams.SuspendLayout();
+            this.grpSpikeParams.SuspendLayout();
+            this.toolStrip.SuspendLayout();
+            this.statusStrip.SuspendLayout();
+            this.SuspendLayout();
+
+            // ---- ToolStrip ----
+            this.toolStrip.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {
+                this.btnAddLine,
+                this.btnDeleteLine
+            });
+            this.toolStrip.Location = new System.Drawing.Point(0, 0);
+            this.toolStrip.Name = "toolStrip";
+            this.toolStrip.Size = new System.Drawing.Size(580, 25);
+            this.toolStrip.TabIndex = 0;
+
+            // btnAddLine
+            this.btnAddLine.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Text;
+            this.btnAddLine.Name = "btnAddLine";
+            this.btnAddLine.Size = new System.Drawing.Size(86, 22);
+            this.btnAddLine.Text = "Add Split Line";
+            this.btnAddLine.Click += new System.EventHandler(this.OnAddSplitLine);
+
+            // btnDeleteLine
+            this.btnDeleteLine.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Text;
+            this.btnDeleteLine.Name = "btnDeleteLine";
+            this.btnDeleteLine.Size = new System.Drawing.Size(68, 22);
+            this.btnDeleteLine.Text = "Delete Line";
+            this.btnDeleteLine.Click += new System.EventHandler(this.OnDeleteSplitLine);
+
+            // ---- StatusStrip ----
+            this.statusStrip.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {
+                this.lblStatus,
+                this.lblCursor
+            });
+            this.statusStrip.Location = new System.Drawing.Point(0, 528);
+            this.statusStrip.Name = "statusStrip";
+            this.statusStrip.Size = new System.Drawing.Size(800, 22);
+            this.statusStrip.TabIndex = 1;
+
+            // lblStatus
+            this.lblStatus.Name = "lblStatus";
+            this.lblStatus.Size = new System.Drawing.Size(100, 17);
+            this.lblStatus.Spring = true;
+            this.lblStatus.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            this.lblStatus.Text = "";
+
+            // lblCursor
+            this.lblCursor.Name = "lblCursor";
+            this.lblCursor.Size = new System.Drawing.Size(150, 17);
+            this.lblCursor.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
+            this.lblCursor.Text = "Cursor: 0.00, 0.00";
+
+            // ---- Settings Panel (right side) ----
+            this.pnlSettings.AutoScroll = true;
+            this.pnlSettings.Dock = System.Windows.Forms.DockStyle.Right;
+            this.pnlSettings.Location = new System.Drawing.Point(580, 25);
+            this.pnlSettings.Name = "pnlSettings";
+            this.pnlSettings.Padding = new System.Windows.Forms.Padding(6);
+            this.pnlSettings.Size = new System.Drawing.Size(220, 503);
+            this.pnlSettings.TabIndex = 2;
+            this.pnlSettings.Controls.Add(this.btnCancel);
+            this.pnlSettings.Controls.Add(this.btnOK);
+            this.pnlSettings.Controls.Add(this.grpSpikeParams);
+            this.pnlSettings.Controls.Add(this.grpTabParams);
+            this.pnlSettings.Controls.Add(this.grpType);
+            this.pnlSettings.Controls.Add(this.grpByCount);
+            this.pnlSettings.Controls.Add(this.grpAutoFit);
+            this.pnlSettings.Controls.Add(this.grpMethod);
+
+            // ---- Split Method Group ----
+            this.grpMethod.Dock = System.Windows.Forms.DockStyle.Top;
+            this.grpMethod.Location = new System.Drawing.Point(6, 6);
+            this.grpMethod.Name = "grpMethod";
+            this.grpMethod.Size = new System.Drawing.Size(208, 95);
+            this.grpMethod.TabIndex = 0;
+            this.grpMethod.TabStop = false;
+            this.grpMethod.Text = "Split Method";
+            this.grpMethod.Controls.Add(this.radByCount);
+            this.grpMethod.Controls.Add(this.radFitToPlate);
+            this.grpMethod.Controls.Add(this.radManual);
+
+            // radManual
+            this.radManual.AutoSize = true;
+            this.radManual.Checked = true;
+            this.radManual.Location = new System.Drawing.Point(10, 20);
+            this.radManual.Name = "radManual";
+            this.radManual.Size = new System.Drawing.Size(65, 19);
+            this.radManual.TabIndex = 0;
+            this.radManual.TabStop = true;
+            this.radManual.Text = "Manual";
+            this.radManual.CheckedChanged += new System.EventHandler(this.OnMethodChanged);
+
+            // radFitToPlate
+            this.radFitToPlate.AutoSize = true;
+            this.radFitToPlate.Location = new System.Drawing.Point(10, 43);
+            this.radFitToPlate.Name = "radFitToPlate";
+            this.radFitToPlate.Size = new System.Drawing.Size(85, 19);
+            this.radFitToPlate.TabIndex = 1;
+            this.radFitToPlate.Text = "Fit to Plate";
+            this.radFitToPlate.CheckedChanged += new System.EventHandler(this.OnMethodChanged);
+
+            // radByCount
+            this.radByCount.AutoSize = true;
+            this.radByCount.Location = new System.Drawing.Point(10, 66);
+            this.radByCount.Name = "radByCount";
+            this.radByCount.Size = new System.Drawing.Size(102, 19);
+            this.radByCount.TabIndex = 2;
+            this.radByCount.Text = "Split by Count";
+            this.radByCount.CheckedChanged += new System.EventHandler(this.OnMethodChanged);
+
+            // ---- Auto-Fit Group ----
+            this.grpAutoFit.Dock = System.Windows.Forms.DockStyle.Top;
+            this.grpAutoFit.Location = new System.Drawing.Point(6, 101);
+            this.grpAutoFit.Name = "grpAutoFit";
+            this.grpAutoFit.Size = new System.Drawing.Size(208, 105);
+            this.grpAutoFit.TabIndex = 1;
+            this.grpAutoFit.TabStop = false;
+            this.grpAutoFit.Text = "Auto-Fit Options";
+            this.grpAutoFit.Visible = false;
+            this.grpAutoFit.Controls.Add(this.nudEdgeSpacing);
+            this.grpAutoFit.Controls.Add(this.lblEdgeSpacing);
+            this.grpAutoFit.Controls.Add(this.nudPlateHeight);
+            this.grpAutoFit.Controls.Add(this.lblPlateHeight);
+            this.grpAutoFit.Controls.Add(this.nudPlateWidth);
+            this.grpAutoFit.Controls.Add(this.lblPlateWidth);
+
+            // lblPlateWidth
+            this.lblPlateWidth.AutoSize = true;
+            this.lblPlateWidth.Location = new System.Drawing.Point(10, 22);
+            this.lblPlateWidth.Name = "lblPlateWidth";
+            this.lblPlateWidth.Size = new System.Drawing.Size(70, 15);
+            this.lblPlateWidth.Text = "Plate Width:";
+
+            // nudPlateWidth
+            this.nudPlateWidth.DecimalPlaces = 2;
+            this.nudPlateWidth.Location = new System.Drawing.Point(110, 20);
+            this.nudPlateWidth.Maximum = new decimal(new int[] { 100000, 0, 0, 0 });
+            this.nudPlateWidth.Minimum = new decimal(new int[] { 1, 0, 0, 0 });
+            this.nudPlateWidth.Name = "nudPlateWidth";
+            this.nudPlateWidth.Size = new System.Drawing.Size(88, 23);
+            this.nudPlateWidth.TabIndex = 0;
+            this.nudPlateWidth.Value = new decimal(new int[] { 120, 0, 0, 0 });
+            this.nudPlateWidth.ValueChanged += new System.EventHandler(this.OnAutoFitValueChanged);
+
+            // lblPlateHeight
+            this.lblPlateHeight.AutoSize = true;
+            this.lblPlateHeight.Location = new System.Drawing.Point(10, 49);
+            this.lblPlateHeight.Name = "lblPlateHeight";
+            this.lblPlateHeight.Size = new System.Drawing.Size(74, 15);
+            this.lblPlateHeight.Text = "Plate Height:";
+
+            // nudPlateHeight
+            this.nudPlateHeight.DecimalPlaces = 2;
+            this.nudPlateHeight.Location = new System.Drawing.Point(110, 47);
+            this.nudPlateHeight.Maximum = new decimal(new int[] { 100000, 0, 0, 0 });
+            this.nudPlateHeight.Minimum = new decimal(new int[] { 1, 0, 0, 0 });
+            this.nudPlateHeight.Name = "nudPlateHeight";
+            this.nudPlateHeight.Size = new System.Drawing.Size(88, 23);
+            this.nudPlateHeight.TabIndex = 1;
+            this.nudPlateHeight.Value = new decimal(new int[] { 60, 0, 0, 0 });
+            this.nudPlateHeight.ValueChanged += new System.EventHandler(this.OnAutoFitValueChanged);
+
+            // lblEdgeSpacing
+            this.lblEdgeSpacing.AutoSize = true;
+            this.lblEdgeSpacing.Location = new System.Drawing.Point(10, 76);
+            this.lblEdgeSpacing.Name = "lblEdgeSpacing";
+            this.lblEdgeSpacing.Size = new System.Drawing.Size(82, 15);
+            this.lblEdgeSpacing.Text = "Edge Spacing:";
+
+            // nudEdgeSpacing
+            this.nudEdgeSpacing.DecimalPlaces = 2;
+            this.nudEdgeSpacing.Location = new System.Drawing.Point(110, 74);
+            this.nudEdgeSpacing.Maximum = new decimal(new int[] { 100, 0, 0, 0 });
+            this.nudEdgeSpacing.Name = "nudEdgeSpacing";
+            this.nudEdgeSpacing.Size = new System.Drawing.Size(88, 23);
+            this.nudEdgeSpacing.TabIndex = 2;
+            this.nudEdgeSpacing.Value = new decimal(new int[] { 5, 0, 0, 131072 });
+            this.nudEdgeSpacing.ValueChanged += new System.EventHandler(this.OnAutoFitValueChanged);
+
+            // ---- By Count Group ----
+            this.grpByCount.Dock = System.Windows.Forms.DockStyle.Top;
+            this.grpByCount.Location = new System.Drawing.Point(6, 206);
+            this.grpByCount.Name = "grpByCount";
+            this.grpByCount.Size = new System.Drawing.Size(208, 78);
+            this.grpByCount.TabIndex = 2;
+            this.grpByCount.TabStop = false;
+            this.grpByCount.Text = "Split by Count";
+            this.grpByCount.Visible = false;
+            this.grpByCount.Controls.Add(this.nudVerticalPieces);
+            this.grpByCount.Controls.Add(this.lblVerticalPieces);
+            this.grpByCount.Controls.Add(this.nudHorizontalPieces);
+            this.grpByCount.Controls.Add(this.lblHorizontalPieces);
+
+            // lblHorizontalPieces
+            this.lblHorizontalPieces.AutoSize = true;
+            this.lblHorizontalPieces.Location = new System.Drawing.Point(10, 22);
+            this.lblHorizontalPieces.Name = "lblHorizontalPieces";
+            this.lblHorizontalPieces.Size = new System.Drawing.Size(72, 15);
+            this.lblHorizontalPieces.Text = "H. Pieces:";
+
+            // nudHorizontalPieces
+            this.nudHorizontalPieces.Location = new System.Drawing.Point(110, 20);
+            this.nudHorizontalPieces.Maximum = new decimal(new int[] { 20, 0, 0, 0 });
+            this.nudHorizontalPieces.Minimum = new decimal(new int[] { 1, 0, 0, 0 });
+            this.nudHorizontalPieces.Name = "nudHorizontalPieces";
+            this.nudHorizontalPieces.Size = new System.Drawing.Size(88, 23);
+            this.nudHorizontalPieces.TabIndex = 0;
+            this.nudHorizontalPieces.Value = new decimal(new int[] { 2, 0, 0, 0 });
+            this.nudHorizontalPieces.ValueChanged += new System.EventHandler(this.OnByCountValueChanged);
+
+            // lblVerticalPieces
+            this.lblVerticalPieces.AutoSize = true;
+            this.lblVerticalPieces.Location = new System.Drawing.Point(10, 49);
+            this.lblVerticalPieces.Name = "lblVerticalPieces";
+            this.lblVerticalPieces.Size = new System.Drawing.Size(63, 15);
+            this.lblVerticalPieces.Text = "V. Pieces:";
+
+            // nudVerticalPieces
+            this.nudVerticalPieces.Location = new System.Drawing.Point(110, 47);
+            this.nudVerticalPieces.Maximum = new decimal(new int[] { 20, 0, 0, 0 });
+            this.nudVerticalPieces.Minimum = new decimal(new int[] { 1, 0, 0, 0 });
+            this.nudVerticalPieces.Name = "nudVerticalPieces";
+            this.nudVerticalPieces.Size = new System.Drawing.Size(88, 23);
+            this.nudVerticalPieces.TabIndex = 1;
+            this.nudVerticalPieces.Value = new decimal(new int[] { 1, 0, 0, 0 });
+            this.nudVerticalPieces.ValueChanged += new System.EventHandler(this.OnByCountValueChanged);
+
+            // ---- Split Type Group ----
+            this.grpType.Dock = System.Windows.Forms.DockStyle.Top;
+            this.grpType.Location = new System.Drawing.Point(6, 284);
+            this.grpType.Name = "grpType";
+            this.grpType.Size = new System.Drawing.Size(208, 95);
+            this.grpType.TabIndex = 3;
+            this.grpType.TabStop = false;
+            this.grpType.Text = "Split Type";
+            this.grpType.Controls.Add(this.radSpike);
+            this.grpType.Controls.Add(this.radTabs);
+            this.grpType.Controls.Add(this.radStraight);
+
+            // radStraight
+            this.radStraight.AutoSize = true;
+            this.radStraight.Checked = true;
+            this.radStraight.Location = new System.Drawing.Point(10, 20);
+            this.radStraight.Name = "radStraight";
+            this.radStraight.Size = new System.Drawing.Size(68, 19);
+            this.radStraight.TabIndex = 0;
+            this.radStraight.TabStop = true;
+            this.radStraight.Text = "Straight";
+            this.radStraight.CheckedChanged += new System.EventHandler(this.OnTypeChanged);
+
+            // radTabs
+            this.radTabs.AutoSize = true;
+            this.radTabs.Location = new System.Drawing.Point(10, 43);
+            this.radTabs.Name = "radTabs";
+            this.radTabs.Size = new System.Drawing.Size(107, 19);
+            this.radTabs.TabIndex = 1;
+            this.radTabs.Text = "Weld-Gap Tabs";
+            this.radTabs.CheckedChanged += new System.EventHandler(this.OnTypeChanged);
+
+            // radSpike
+            this.radSpike.AutoSize = true;
+            this.radSpike.Location = new System.Drawing.Point(10, 66);
+            this.radSpike.Name = "radSpike";
+            this.radSpike.Size = new System.Drawing.Size(99, 19);
+            this.radSpike.TabIndex = 2;
+            this.radSpike.Text = "Spike-Groove";
+            this.radSpike.CheckedChanged += new System.EventHandler(this.OnTypeChanged);
+
+            // ---- Tab Parameters Group ----
+            this.grpTabParams.Dock = System.Windows.Forms.DockStyle.Top;
+            this.grpTabParams.Location = new System.Drawing.Point(6, 379);
+            this.grpTabParams.Name = "grpTabParams";
+            this.grpTabParams.Size = new System.Drawing.Size(208, 105);
+            this.grpTabParams.TabIndex = 4;
+            this.grpTabParams.TabStop = false;
+            this.grpTabParams.Text = "Tab Parameters";
+            this.grpTabParams.Visible = false;
+            this.grpTabParams.Controls.Add(this.nudTabCount);
+            this.grpTabParams.Controls.Add(this.lblTabCount);
+            this.grpTabParams.Controls.Add(this.nudTabHeight);
+            this.grpTabParams.Controls.Add(this.lblTabHeight);
+            this.grpTabParams.Controls.Add(this.nudTabWidth);
+            this.grpTabParams.Controls.Add(this.lblTabWidth);
+
+            // lblTabWidth
+            this.lblTabWidth.AutoSize = true;
+            this.lblTabWidth.Location = new System.Drawing.Point(10, 22);
+            this.lblTabWidth.Name = "lblTabWidth";
+            this.lblTabWidth.Size = new System.Drawing.Size(65, 15);
+            this.lblTabWidth.Text = "Tab Width:";
+
+            // nudTabWidth
+            this.nudTabWidth.DecimalPlaces = 2;
+            this.nudTabWidth.Location = new System.Drawing.Point(110, 20);
+            this.nudTabWidth.Maximum = new decimal(new int[] { 1000, 0, 0, 0 });
+            this.nudTabWidth.Minimum = new decimal(new int[] { 1, 0, 0, 131072 });
+            this.nudTabWidth.Name = "nudTabWidth";
+            this.nudTabWidth.Size = new System.Drawing.Size(88, 23);
+            this.nudTabWidth.TabIndex = 0;
+            this.nudTabWidth.Value = new decimal(new int[] { 5, 0, 0, 65536 });
+
+            // lblTabHeight
+            this.lblTabHeight.AutoSize = true;
+            this.lblTabHeight.Location = new System.Drawing.Point(10, 49);
+            this.lblTabHeight.Name = "lblTabHeight";
+            this.lblTabHeight.Size = new System.Drawing.Size(69, 15);
+            this.lblTabHeight.Text = "Tab Height:";
+
+            // nudTabHeight
+            this.nudTabHeight.DecimalPlaces = 2;
+            this.nudTabHeight.Location = new System.Drawing.Point(110, 47);
+            this.nudTabHeight.Maximum = new decimal(new int[] { 100, 0, 0, 0 });
+            this.nudTabHeight.Minimum = new decimal(new int[] { 1, 0, 0, 131072 });
+            this.nudTabHeight.Name = "nudTabHeight";
+            this.nudTabHeight.Size = new System.Drawing.Size(88, 23);
+            this.nudTabHeight.TabIndex = 1;
+            this.nudTabHeight.Value = new decimal(new int[] { 1, 0, 0, 65536 });
+
+            // lblTabCount
+            this.lblTabCount.AutoSize = true;
+            this.lblTabCount.Location = new System.Drawing.Point(10, 76);
+            this.lblTabCount.Name = "lblTabCount";
+            this.lblTabCount.Size = new System.Drawing.Size(64, 15);
+            this.lblTabCount.Text = "Tab Count:";
+
+            // nudTabCount
+            this.nudTabCount.Location = new System.Drawing.Point(110, 74);
+            this.nudTabCount.Maximum = new decimal(new int[] { 50, 0, 0, 0 });
+            this.nudTabCount.Minimum = new decimal(new int[] { 1, 0, 0, 0 });
+            this.nudTabCount.Name = "nudTabCount";
+            this.nudTabCount.Size = new System.Drawing.Size(88, 23);
+            this.nudTabCount.TabIndex = 2;
+            this.nudTabCount.Value = new decimal(new int[] { 3, 0, 0, 0 });
+
+            // ---- Spike Parameters Group ----
+            this.grpSpikeParams.Dock = System.Windows.Forms.DockStyle.Top;
+            this.grpSpikeParams.Location = new System.Drawing.Point(6, 484);
+            this.grpSpikeParams.Name = "grpSpikeParams";
+            this.grpSpikeParams.Size = new System.Drawing.Size(208, 105);
+            this.grpSpikeParams.TabIndex = 5;
+            this.grpSpikeParams.TabStop = false;
+            this.grpSpikeParams.Text = "Spike Parameters";
+            this.grpSpikeParams.Visible = false;
+            this.grpSpikeParams.Controls.Add(this.nudSpikePairCount);
+            this.grpSpikeParams.Controls.Add(this.lblSpikePairCount);
+            this.grpSpikeParams.Controls.Add(this.nudSpikeAngle);
+            this.grpSpikeParams.Controls.Add(this.lblSpikeAngle);
+            this.grpSpikeParams.Controls.Add(this.nudSpikeDepth);
+            this.grpSpikeParams.Controls.Add(this.lblSpikeDepth);
+
+            // lblSpikeDepth
+            this.lblSpikeDepth.AutoSize = true;
+            this.lblSpikeDepth.Location = new System.Drawing.Point(10, 22);
+            this.lblSpikeDepth.Name = "lblSpikeDepth";
+            this.lblSpikeDepth.Size = new System.Drawing.Size(74, 15);
+            this.lblSpikeDepth.Text = "Spike Depth:";
+
+            // nudSpikeDepth
+            this.nudSpikeDepth.DecimalPlaces = 2;
+            this.nudSpikeDepth.Location = new System.Drawing.Point(110, 20);
+            this.nudSpikeDepth.Maximum = new decimal(new int[] { 100, 0, 0, 0 });
+            this.nudSpikeDepth.Minimum = new decimal(new int[] { 1, 0, 0, 131072 });
+            this.nudSpikeDepth.Name = "nudSpikeDepth";
+            this.nudSpikeDepth.Size = new System.Drawing.Size(88, 23);
+            this.nudSpikeDepth.TabIndex = 0;
+            this.nudSpikeDepth.Value = new decimal(new int[] { 5, 0, 0, 65536 });
+
+            // lblSpikeAngle
+            this.lblSpikeAngle.AutoSize = true;
+            this.lblSpikeAngle.Location = new System.Drawing.Point(10, 49);
+            this.lblSpikeAngle.Name = "lblSpikeAngle";
+            this.lblSpikeAngle.Size = new System.Drawing.Size(74, 15);
+            this.lblSpikeAngle.Text = "Spike Angle:";
+
+            // nudSpikeAngle
+            this.nudSpikeAngle.DecimalPlaces = 1;
+            this.nudSpikeAngle.Location = new System.Drawing.Point(110, 47);
+            this.nudSpikeAngle.Maximum = new decimal(new int[] { 89, 0, 0, 0 });
+            this.nudSpikeAngle.Minimum = new decimal(new int[] { 10, 0, 0, 0 });
+            this.nudSpikeAngle.Name = "nudSpikeAngle";
+            this.nudSpikeAngle.Size = new System.Drawing.Size(88, 23);
+            this.nudSpikeAngle.TabIndex = 1;
+            this.nudSpikeAngle.Value = new decimal(new int[] { 45, 0, 0, 0 });
+
+            // lblSpikePairCount
+            this.lblSpikePairCount.AutoSize = true;
+            this.lblSpikePairCount.Location = new System.Drawing.Point(10, 76);
+            this.lblSpikePairCount.Name = "lblSpikePairCount";
+            this.lblSpikePairCount.Size = new System.Drawing.Size(65, 15);
+            this.lblSpikePairCount.Text = "Pair Count:";
+
+            // nudSpikePairCount
+            this.nudSpikePairCount.Location = new System.Drawing.Point(110, 74);
+            this.nudSpikePairCount.Maximum = new decimal(new int[] { 50, 0, 0, 0 });
+            this.nudSpikePairCount.Minimum = new decimal(new int[] { 1, 0, 0, 0 });
+            this.nudSpikePairCount.Name = "nudSpikePairCount";
+            this.nudSpikePairCount.Size = new System.Drawing.Size(88, 23);
+            this.nudSpikePairCount.TabIndex = 2;
+            this.nudSpikePairCount.Value = new decimal(new int[] { 3, 0, 0, 0 });
+
+            // ---- OK / Cancel Buttons ----
+            this.btnOK.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
+            this.btnOK.Location = new System.Drawing.Point(30, 468);
+            this.btnOK.Name = "btnOK";
+            this.btnOK.Size = new System.Drawing.Size(80, 28);
+            this.btnOK.TabIndex = 6;
+            this.btnOK.Text = "OK";
+            this.btnOK.UseVisualStyleBackColor = true;
+            this.btnOK.Click += new System.EventHandler(this.OnOK);
+
+            this.btnCancel.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
+            this.btnCancel.DialogResult = System.Windows.Forms.DialogResult.Cancel;
+            this.btnCancel.Location = new System.Drawing.Point(120, 468);
+            this.btnCancel.Name = "btnCancel";
+            this.btnCancel.Size = new System.Drawing.Size(80, 28);
+            this.btnCancel.TabIndex = 7;
+            this.btnCancel.Text = "Cancel";
+            this.btnCancel.UseVisualStyleBackColor = true;
+            this.btnCancel.Click += new System.EventHandler(this.OnCancel);
+
+            // ---- Preview Panel (fills remaining space) ----
+            this.pnlPreview.Dock = System.Windows.Forms.DockStyle.Fill;
+            this.pnlPreview.Location = new System.Drawing.Point(0, 25);
+            this.pnlPreview.Name = "pnlPreview";
+            this.pnlPreview.Size = new System.Drawing.Size(580, 503);
+            this.pnlPreview.TabIndex = 3;
+            this.pnlPreview.Paint += new System.Windows.Forms.PaintEventHandler(this.OnPreviewPaint);
+            this.pnlPreview.MouseDown += new System.Windows.Forms.MouseEventHandler(this.OnPreviewMouseDown);
+            this.pnlPreview.MouseMove += new System.Windows.Forms.MouseEventHandler(this.OnPreviewMouseMove);
+            this.pnlPreview.MouseUp += new System.Windows.Forms.MouseEventHandler(this.OnPreviewMouseUp);
+            this.pnlPreview.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.OnPreviewMouseWheel);
+
+            // ---- SplitDrawingForm ----
+            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.None;
+            this.CancelButton = this.btnCancel;
+            this.ClientSize = new System.Drawing.Size(800, 550);
+            this.Controls.Add(this.pnlPreview);
+            this.Controls.Add(this.pnlSettings);
+            this.Controls.Add(this.statusStrip);
+            this.Controls.Add(this.toolStrip);
+            this.MinimumSize = new System.Drawing.Size(600, 450);
+            this.Name = "SplitDrawingForm";
+            this.ShowIcon = false;
+            this.ShowInTaskbar = false;
+            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterParent;
+            this.Text = "Split Drawing";
+
+            ((System.ComponentModel.ISupportInitialize)(this.nudPlateWidth)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudPlateHeight)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudEdgeSpacing)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudHorizontalPieces)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudVerticalPieces)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudTabWidth)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudTabHeight)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudTabCount)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudSpikeDepth)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudSpikeAngle)).EndInit();
+            ((System.ComponentModel.ISupportInitialize)(this.nudSpikePairCount)).EndInit();
+            this.pnlSettings.ResumeLayout(false);
+            this.grpMethod.ResumeLayout(false);
+            this.grpMethod.PerformLayout();
+            this.grpAutoFit.ResumeLayout(false);
+            this.grpAutoFit.PerformLayout();
+            this.grpByCount.ResumeLayout(false);
+            this.grpByCount.PerformLayout();
+            this.grpType.ResumeLayout(false);
+            this.grpType.PerformLayout();
+            this.grpTabParams.ResumeLayout(false);
+            this.grpTabParams.PerformLayout();
+            this.grpSpikeParams.ResumeLayout(false);
+            this.grpSpikeParams.PerformLayout();
+            this.toolStrip.ResumeLayout(false);
+            this.toolStrip.PerformLayout();
+            this.statusStrip.ResumeLayout(false);
+            this.statusStrip.PerformLayout();
+            this.ResumeLayout(false);
+            this.PerformLayout();
+        }
+
+        #endregion
+
+        private System.Windows.Forms.Panel pnlPreview;
+        private System.Windows.Forms.Panel pnlSettings;
+        private System.Windows.Forms.ToolStrip toolStrip;
+        private System.Windows.Forms.ToolStripButton btnAddLine;
+        private System.Windows.Forms.ToolStripButton btnDeleteLine;
+        private System.Windows.Forms.StatusStrip statusStrip;
+        private System.Windows.Forms.ToolStripStatusLabel lblStatus;
+        private System.Windows.Forms.ToolStripStatusLabel lblCursor;
+
+        private System.Windows.Forms.GroupBox grpMethod;
+        private System.Windows.Forms.RadioButton radManual;
+        private System.Windows.Forms.RadioButton radFitToPlate;
+        private System.Windows.Forms.RadioButton radByCount;
+
+        private System.Windows.Forms.GroupBox grpAutoFit;
+        private System.Windows.Forms.Label lblPlateWidth;
+        private System.Windows.Forms.NumericUpDown nudPlateWidth;
+        private System.Windows.Forms.Label lblPlateHeight;
+        private System.Windows.Forms.NumericUpDown nudPlateHeight;
+        private System.Windows.Forms.Label lblEdgeSpacing;
+        private System.Windows.Forms.NumericUpDown nudEdgeSpacing;
+
+        private System.Windows.Forms.GroupBox grpByCount;
+        private System.Windows.Forms.Label lblHorizontalPieces;
+        private System.Windows.Forms.NumericUpDown nudHorizontalPieces;
+        private System.Windows.Forms.Label lblVerticalPieces;
+        private System.Windows.Forms.NumericUpDown nudVerticalPieces;
+
+        private System.Windows.Forms.GroupBox grpType;
+        private System.Windows.Forms.RadioButton radStraight;
+        private System.Windows.Forms.RadioButton radTabs;
+        private System.Windows.Forms.RadioButton radSpike;
+
+        private System.Windows.Forms.GroupBox grpTabParams;
+        private System.Windows.Forms.Label lblTabWidth;
+        private System.Windows.Forms.NumericUpDown nudTabWidth;
+        private System.Windows.Forms.Label lblTabHeight;
+        private System.Windows.Forms.NumericUpDown nudTabHeight;
+        private System.Windows.Forms.Label lblTabCount;
+        private System.Windows.Forms.NumericUpDown nudTabCount;
+
+        private System.Windows.Forms.GroupBox grpSpikeParams;
+        private System.Windows.Forms.Label lblSpikeDepth;
+        private System.Windows.Forms.NumericUpDown nudSpikeDepth;
+        private System.Windows.Forms.Label lblSpikeAngle;
+        private System.Windows.Forms.NumericUpDown nudSpikeAngle;
+        private System.Windows.Forms.Label lblSpikePairCount;
+        private System.Windows.Forms.NumericUpDown nudSpikePairCount;
+
+        private System.Windows.Forms.Button btnOK;
+        private System.Windows.Forms.Button btnCancel;
+    }
+}
diff --git a/OpenNest/Forms/SplitDrawingForm.cs b/OpenNest/Forms/SplitDrawingForm.cs
new file mode 100644
index 0000000..a982232
--- /dev/null
+++ b/OpenNest/Forms/SplitDrawingForm.cs
@@ -0,0 +1,363 @@
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Drawing.Drawing2D;
+using System.Linq;
+using System.Windows.Forms;
+using OpenNest.Converters;
+using OpenNest.Geometry;
+
+namespace OpenNest.Forms;
+
+public partial class SplitDrawingForm : Form
+{
+    private readonly Drawing _drawing;
+    private readonly List<Entity> _drawingEntities;
+    private readonly Box _drawingBounds;
+    private readonly List<SplitLine> _splitLines = new();
+    private CutOffAxis _currentAxis = CutOffAxis.Vertical;
+    private bool _placingLine;
+
+    // Zoom/pan state
+    private float _zoom = 1f;
+    private PointF _pan;
+    private Point _lastMouse;
+    private bool _panning;
+
+    // Snap threshold in screen pixels
+    private const double SnapThreshold = 5.0;
+
+    public List<Drawing> ResultDrawings { get; private set; }
+
+    public SplitDrawingForm(Drawing drawing)
+    {
+        InitializeComponent();
+
+        // Enable double buffering on the preview panel to reduce flicker
+        typeof(Panel).InvokeMember(
+            "DoubleBuffered",
+            System.Reflection.BindingFlags.SetProperty | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic,
+            null, pnlPreview, new object[] { true });
+
+        _drawing = drawing;
+        _drawingEntities = ConvertProgram.ToGeometry(drawing.Program);
+        _drawingBounds = drawing.Program.BoundingBox();
+
+        Text = $"Split Drawing: {drawing.Name}";
+        UpdateUI();
+        FitToView();
+    }
+
+    // --- Split Method Selection ---
+
+    private void OnMethodChanged(object sender, EventArgs e)
+    {
+        grpAutoFit.Visible = radFitToPlate.Checked;
+        grpByCount.Visible = radByCount.Checked;
+
+        if (radFitToPlate.Checked || radByCount.Checked)
+            RecalculateAutoSplitLines();
+    }
+
+    private void RecalculateAutoSplitLines()
+    {
+        _splitLines.Clear();
+
+        if (radFitToPlate.Checked)
+        {
+            var plateW = (double)nudPlateWidth.Value;
+            var plateH = (double)nudPlateHeight.Value;
+            var spacing = (double)nudEdgeSpacing.Value;
+            var overhang = GetCurrentParameters().FeatureOverhang;
+            _splitLines.AddRange(AutoSplitCalculator.FitToPlate(_drawingBounds, plateW, plateH, spacing, overhang));
+        }
+        else if (radByCount.Checked)
+        {
+            var hPieces = (int)nudHorizontalPieces.Value;
+            var vPieces = (int)nudVerticalPieces.Value;
+            _splitLines.AddRange(AutoSplitCalculator.SplitByCount(_drawingBounds, hPieces, vPieces));
+        }
+
+        UpdateUI();
+        pnlPreview.Invalidate();
+    }
+
+    private void OnAutoFitValueChanged(object sender, EventArgs e)
+    {
+        if (radFitToPlate.Checked)
+            RecalculateAutoSplitLines();
+    }
+
+    private void OnByCountValueChanged(object sender, EventArgs e)
+    {
+        if (radByCount.Checked)
+            RecalculateAutoSplitLines();
+    }
+
+    // --- Split Type Selection ---
+
+    private void OnTypeChanged(object sender, EventArgs e)
+    {
+        grpTabParams.Visible = radTabs.Checked;
+        grpSpikeParams.Visible = radSpike.Checked;
+        if (radFitToPlate.Checked)
+            RecalculateAutoSplitLines(); // overhang changed
+        pnlPreview.Invalidate();
+    }
+
+    private SplitParameters GetCurrentParameters()
+    {
+        var p = new SplitParameters();
+        if (radTabs.Checked)
+        {
+            p.Type = SplitType.WeldGapTabs;
+            p.TabWidth = (double)nudTabWidth.Value;
+            p.TabHeight = (double)nudTabHeight.Value;
+            p.TabCount = (int)nudTabCount.Value;
+        }
+        else if (radSpike.Checked)
+        {
+            p.Type = SplitType.SpikeGroove;
+            p.SpikeDepth = (double)nudSpikeDepth.Value;
+            p.SpikeAngle = (double)nudSpikeAngle.Value;
+            p.SpikePairCount = (int)nudSpikePairCount.Value;
+        }
+        return p;
+    }
+
+    // --- Manual Split Line Placement ---
+
+    private void OnPreviewMouseDown(object sender, MouseEventArgs e)
+    {
+        if (e.Button == MouseButtons.Left && radManual.Checked && _placingLine)
+        {
+            var pt = ScreenToDrawing(e.Location);
+            var snapped = SnapToMidpoint(pt);
+            var position = _currentAxis == CutOffAxis.Vertical ? snapped.X : snapped.Y;
+            _splitLines.Add(new SplitLine(position, _currentAxis));
+            UpdateUI();
+            pnlPreview.Invalidate();
+        }
+        else if (e.Button == MouseButtons.Middle)
+        {
+            _panning = true;
+            _lastMouse = e.Location;
+        }
+    }
+
+    private void OnPreviewMouseMove(object sender, MouseEventArgs e)
+    {
+        if (_panning)
+        {
+            _pan.X += e.X - _lastMouse.X;
+            _pan.Y += e.Y - _lastMouse.Y;
+            _lastMouse = e.Location;
+            pnlPreview.Invalidate();
+        }
+
+        var drawPt = ScreenToDrawing(e.Location);
+        lblCursor.Text = $"Cursor: {drawPt.X:F2}, {drawPt.Y:F2}";
+    }
+
+    private void OnPreviewMouseUp(object sender, MouseEventArgs e)
+    {
+        if (e.Button == MouseButtons.Middle)
+            _panning = false;
+    }
+
+    private void OnPreviewMouseWheel(object sender, MouseEventArgs e)
+    {
+        var factor = e.Delta > 0 ? 1.1f : 0.9f;
+        _zoom *= factor;
+        pnlPreview.Invalidate();
+    }
+
+    protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
+    {
+        if (keyData == Keys.Space)
+        {
+            _currentAxis = _currentAxis == CutOffAxis.Vertical ? CutOffAxis.Horizontal : CutOffAxis.Vertical;
+            return true;
+        }
+        if (keyData == Keys.Escape)
+        {
+            _placingLine = false;
+            return true;
+        }
+        return base.ProcessCmdKey(ref msg, keyData);
+    }
+
+    private Vector SnapToMidpoint(Vector pt)
+    {
+        var midX = _drawingBounds.Center.X;
+        var midY = _drawingBounds.Center.Y;
+        var threshold = SnapThreshold / _zoom;
+
+        if (_currentAxis == CutOffAxis.Vertical && System.Math.Abs(pt.X - midX) < threshold)
+            return new Vector(midX, pt.Y);
+        if (_currentAxis == CutOffAxis.Horizontal && System.Math.Abs(pt.Y - midY) < threshold)
+            return new Vector(pt.X, midY);
+        return pt;
+    }
+
+    // --- Rendering ---
+
+    private void OnPreviewPaint(object sender, PaintEventArgs e)
+    {
+        var g = e.Graphics;
+        g.SmoothingMode = SmoothingMode.AntiAlias;
+        g.Clear(Color.FromArgb(26, 26, 26));
+
+        g.TranslateTransform(_pan.X, _pan.Y);
+        g.ScaleTransform(_zoom, -_zoom); // flip Y for CNC coordinates
+
+        // Draw part outline
+        using var partPen = new Pen(Color.LightGray, 1f / _zoom);
+        DrawEntities(g, _drawingEntities, partPen);
+
+        // Draw split lines
+        using var splitPen = new Pen(Color.FromArgb(255, 82, 82), 1f / _zoom);
+        splitPen.DashStyle = DashStyle.Dash;
+        foreach (var sl in _splitLines)
+        {
+            if (sl.Axis == CutOffAxis.Vertical)
+                g.DrawLine(splitPen, (float)sl.Position, (float)(_drawingBounds.Bottom - 10), (float)sl.Position, (float)(_drawingBounds.Top + 10));
+            else
+                g.DrawLine(splitPen, (float)(_drawingBounds.Left - 10), (float)sl.Position, (float)(_drawingBounds.Right + 10), (float)sl.Position);
+        }
+
+        // Draw piece color overlays
+        DrawPieceOverlays(g);
+    }
+
+    private void DrawEntities(Graphics g, List<Entity> entities, Pen pen)
+    {
+        foreach (var entity in entities)
+        {
+            if (entity is Line line)
+                g.DrawLine(pen, (float)line.StartPoint.X, (float)line.StartPoint.Y, (float)line.EndPoint.X, (float)line.EndPoint.Y);
+            else if (entity is Arc arc)
+            {
+                var rect = new RectangleF(
+                    (float)(arc.Center.X - arc.Radius),
+                    (float)(arc.Center.Y - arc.Radius),
+                    (float)(arc.Radius * 2),
+                    (float)(arc.Radius * 2));
+                var startDeg = (float)OpenNest.Math.Angle.ToDegrees(arc.StartAngle);
+                var sweepDeg = (float)OpenNest.Math.Angle.ToDegrees(arc.EndAngle - arc.StartAngle);
+                if (rect.Width > 0 && rect.Height > 0)
+                    g.DrawArc(pen, rect, startDeg, sweepDeg);
+            }
+        }
+    }
+
+    private static readonly Color[] PieceColors =
+    {
+        Color.FromArgb(40, 79, 195, 247),
+        Color.FromArgb(40, 129, 199, 132),
+        Color.FromArgb(40, 255, 183, 77),
+        Color.FromArgb(40, 206, 147, 216),
+        Color.FromArgb(40, 255, 138, 128),
+        Color.FromArgb(40, 128, 222, 234)
+    };
+
+    private void DrawPieceOverlays(Graphics g)
+    {
+        // Simple region overlay based on split lines and bounding box
+        var regions = BuildPreviewRegions();
+        for (var i = 0; i < regions.Count; i++)
+        {
+            var color = PieceColors[i % PieceColors.Length];
+            using var brush = new SolidBrush(color);
+            var r = regions[i];
+            g.FillRectangle(brush, (float)r.Left, (float)r.Bottom, (float)r.Width, (float)r.Length);
+        }
+    }
+
+    private List<Box> BuildPreviewRegions()
+    {
+        var verticals = _splitLines.Where(l => l.Axis == CutOffAxis.Vertical).OrderBy(l => l.Position).ToList();
+        var horizontals = _splitLines.Where(l => l.Axis == CutOffAxis.Horizontal).OrderBy(l => l.Position).ToList();
+
+        var xEdges = new List<double> { _drawingBounds.Left };
+        xEdges.AddRange(verticals.Select(v => v.Position));
+        xEdges.Add(_drawingBounds.Right);
+
+        var yEdges = new List<double> { _drawingBounds.Bottom };
+        yEdges.AddRange(horizontals.Select(h => h.Position));
+        yEdges.Add(_drawingBounds.Top);
+
+        var regions = new List<Box>();
+        for (var yi = 0; yi < yEdges.Count - 1; yi++)
+            for (var xi = 0; xi < xEdges.Count - 1; xi++)
+                regions.Add(new Box(xEdges[xi], yEdges[yi], xEdges[xi + 1] - xEdges[xi], yEdges[yi + 1] - yEdges[yi]));
+
+        return regions;
+    }
+
+    // --- Coordinate transforms ---
+
+    private Vector ScreenToDrawing(Point screen)
+    {
+        var x = (screen.X - _pan.X) / _zoom;
+        var y = -(screen.Y - _pan.Y) / _zoom; // flip Y
+        return new Vector(x, y);
+    }
+
+    private void FitToView()
+    {
+        if (_drawingBounds.Width <= 0 || _drawingBounds.Length <= 0) return;
+        var pad = 40f;
+        var scaleX = (pnlPreview.Width - pad * 2) / (float)_drawingBounds.Width;
+        var scaleY = (pnlPreview.Height - pad * 2) / (float)_drawingBounds.Length;
+        _zoom = System.Math.Min(scaleX, scaleY);
+        _pan = new PointF(
+            pad - (float)_drawingBounds.Left * _zoom,
+            pnlPreview.Height - pad + (float)_drawingBounds.Bottom * _zoom);
+    }
+
+    // --- OK/Cancel ---
+
+    private void OnOK(object sender, EventArgs e)
+    {
+        if (_splitLines.Count == 0)
+        {
+            MessageBox.Show("No split lines defined.", "Split Drawing", MessageBoxButtons.OK, MessageBoxIcon.Information);
+            return;
+        }
+
+        ResultDrawings = DrawingSplitter.Split(_drawing, _splitLines, GetCurrentParameters());
+        DialogResult = DialogResult.OK;
+        Close();
+    }
+
+    private void OnCancel(object sender, EventArgs e)
+    {
+        DialogResult = DialogResult.Cancel;
+        Close();
+    }
+
+    // --- Toolbar ---
+
+    private void OnAddSplitLine(object sender, EventArgs e)
+    {
+        radManual.Checked = true;
+        _placingLine = true;
+    }
+
+    private void OnDeleteSplitLine(object sender, EventArgs e)
+    {
+        if (_splitLines.Count > 0)
+        {
+            _splitLines.RemoveAt(_splitLines.Count - 1);
+            UpdateUI();
+            pnlPreview.Invalidate();
+        }
+    }
+
+    private void UpdateUI()
+    {
+        var pieceCount = _splitLines.Count == 0 ? 1 : BuildPreviewRegions().Count;
+        lblStatus.Text = $"Part: {_drawingBounds.Width:F2} x {_drawingBounds.Length:F2} | {_splitLines.Count} split lines | {pieceCount} pieces";
+    }
+}