diff --git a/MatterControlLib/DesignTools/Operations/Image/ImageToPathObject3D_2.cs b/MatterControlLib/DesignTools/Operations/Image/ImageToPathObject3D_2.cs
index 3d12ef3a4..bb61b6843 100644
--- a/MatterControlLib/DesignTools/Operations/Image/ImageToPathObject3D_2.cs
+++ b/MatterControlLib/DesignTools/Operations/Image/ImageToPathObject3D_2.cs
@@ -348,16 +348,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					Histogram.RangeEnd = .9;
 				}
 
-				if (AnalysisType != AnalysisTypes.Transparency)
-				{
-					Histogram.BuildHistogramFromImage(SourceImage, AnalysisType);
-					var _ = Image; // call this to make sure it is built
-					Histogram.RebuildAlphaImage(SourceImage, alphaImage, Image, AnalysisType);
-				}
-				else
-				{
-					Image?.CopyFrom(SourceImage);
-				}
+				CopyNewImageData();
 				await Rebuild();
 
 				this.ReloadEditorPannel();
@@ -368,12 +359,27 @@ namespace MatterHackers.MatterControl.DesignTools
 			}
 			else if (SheetObject3D.NeedsRebuild(this, invalidateArgs))
 			{
-				await Rebuild();
+                CopyNewImageData();
+                await Rebuild();
 			}
 
 			base.OnInvalidate(invalidateArgs);
 		}
 
+		private void CopyNewImageData()
+		{
+			if (AnalysisType != AnalysisTypes.Transparency)
+			{
+				Histogram.BuildHistogramFromImage(SourceImage, AnalysisType);
+				var _ = Image; // call this to make sure it is built
+				Histogram.RebuildAlphaImage(SourceImage, alphaImage, Image, AnalysisType);
+			}
+			else
+			{
+				Image?.CopyFrom(SourceImage);
+			}
+		}
+
 		public override Task Rebuild()
 		{
 			this.DebugDepth("Rebuild");
diff --git a/MatterControlLib/DesignTools/Operations/Path/LinearExtrudeObject3D.cs b/MatterControlLib/DesignTools/Operations/Path/LinearExtrudeObject3D.cs
index 3cc090909..494593f65 100644
--- a/MatterControlLib/DesignTools/Operations/Path/LinearExtrudeObject3D.cs
+++ b/MatterControlLib/DesignTools/Operations/Path/LinearExtrudeObject3D.cs
@@ -32,6 +32,7 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Threading;
 using System.Threading.Tasks;
+using CsvHelper;
 using MatterHackers.Agg.UI;
 using MatterHackers.Agg.VertexSource;
 using MatterHackers.DataConverters3D;
@@ -107,23 +108,27 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 			Name = "Linear Extrude".Localize();
 		}
 
-		public override async void OnInvalidate(InvalidateArgs eventArgs)
+		public override async void OnInvalidate(InvalidateArgs invalidateArgs)
 		{
-			if ((eventArgs.InvalidateType.HasFlag(InvalidateType.Path)
-					|| eventArgs.InvalidateType.HasFlag(InvalidateType.Children))
-				&& eventArgs.Source != this
+			if ((invalidateArgs.InvalidateType.HasFlag(InvalidateType.Path)
+					|| invalidateArgs.InvalidateType.HasFlag(InvalidateType.Children))
+				&& invalidateArgs.Source != this
 				&& !RebuildLocked)
 			{
 				await Rebuild();
 			}
-			else if (eventArgs.InvalidateType.HasFlag(InvalidateType.Properties)
-				&& eventArgs.Source == this)
+			else if (invalidateArgs.InvalidateType.HasFlag(InvalidateType.Properties)
+				&& invalidateArgs.Source == this)
 			{
 				await Rebuild();
 			}
-			else
-			{
-				base.OnInvalidate(eventArgs);
+            else if (SheetObject3D.NeedsRebuild(this, invalidateArgs))
+            {
+                await Rebuild();
+            }
+            else
+            {
+				base.OnInvalidate(invalidateArgs);
 			}
 		}
 
diff --git a/MatterControlLib/DesignTools/Operations/Path/RevolveObject3D.cs b/MatterControlLib/DesignTools/Operations/Path/RevolveObject3D.cs
index 44bc1a73e..55157ca8d 100644
--- a/MatterControlLib/DesignTools/Operations/Path/RevolveObject3D.cs
+++ b/MatterControlLib/DesignTools/Operations/Path/RevolveObject3D.cs
@@ -100,23 +100,23 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 			Name = "Revolve".Localize();
 		}
 
-		public override async void OnInvalidate(InvalidateArgs eventArgs)
+		public override async void OnInvalidate(InvalidateArgs invalidateArgs)
 		{
-			if ((eventArgs.InvalidateType.HasFlag(InvalidateType.Path)
-					|| eventArgs.InvalidateType.HasFlag(InvalidateType.Children))
-				&& eventArgs.Source != this
+			if ((invalidateArgs.InvalidateType.HasFlag(InvalidateType.Path)
+					|| invalidateArgs.InvalidateType.HasFlag(InvalidateType.Children))
+				&& invalidateArgs.Source != this
 				&& !RebuildLocked)
 			{
 				await Rebuild();
 			}
-			else if (eventArgs.InvalidateType.HasFlag(InvalidateType.Properties)
-				&& eventArgs.Source == this)
+			else if (invalidateArgs.InvalidateType.HasFlag(InvalidateType.Properties)
+				&& invalidateArgs.Source == this)
 			{
 				await Rebuild();
 			}
 			else
 			{
-				base.OnInvalidate(eventArgs);
+				base.OnInvalidate(invalidateArgs);
 			}
 		}
 
diff --git a/MatterControlLib/DesignTools/Sheets/SheetData.cs b/MatterControlLib/DesignTools/Sheets/SheetData.cs
index b7d293c1a..772c09b47 100644
--- a/MatterControlLib/DesignTools/Sheets/SheetData.cs
+++ b/MatterControlLib/DesignTools/Sheets/SheetData.cs
@@ -66,22 +66,27 @@ namespace MatterHackers.MatterControl.DesignTools
 
                 var cell = this[cellId];
 
-				var expression = cell.Expression;
-
-                if (expression.StartsWith("="))
+				if (cell != null)
 				{
-                    expression = expression.Substring(1);
-                    var evaluator = new Expression(expression.ToLower());
-                    AddConstants(evaluator);
-                    var value = evaluator.calculate();
+					var expression = cell.Expression;
 
-                    return value.ToString();
-                }
-                else
-				{
-					// return the expression without evaluation
-					return expression;
+					if (expression.StartsWith("="))
+					{
+						expression = expression.Substring(1);
+						var evaluator = new Expression(expression.ToLower());
+						AddConstants(evaluator);
+						var value = evaluator.calculate();
+
+						return value.ToString();
+					}
+					else
+					{
+						// return the expression without evaluation
+						return expression;
+					}
 				}
+
+				return "0";
             }
         }
 
diff --git a/MatterControlLib/DesignTools/Sheets/SheetObject3D.cs b/MatterControlLib/DesignTools/Sheets/SheetObject3D.cs
index 3d6404fc2..d3903c6bf 100644
--- a/MatterControlLib/DesignTools/Sheets/SheetObject3D.cs
+++ b/MatterControlLib/DesignTools/Sheets/SheetObject3D.cs
@@ -519,9 +519,14 @@ namespace MatterHackers.MatterControl.DesignTools
 					}
 				}
 
-				return (T)(object)0;
-			}
-		}
+                if (typeof(T) == typeof(double))
+                {
+                    return (T)(object)0;
+                }
+
+				return (T)(object)(int)0;
+            }
+        }
 
 		/// <summary>
 		/// Find the sheet that the given item will reference
diff --git a/Submodules/MatterSlice b/Submodules/MatterSlice
index e437d4463..6f3ef82f9 160000
--- a/Submodules/MatterSlice
+++ b/Submodules/MatterSlice
@@ -1 +1 @@
-Subproject commit e437d4463e3bd565ea7c1fb6dbc6c5c1348c802c
+Subproject commit 6f3ef82f9cad3ba1f1419c427336de60fbf6070e
diff --git a/Submodules/agg-sharp b/Submodules/agg-sharp
index 1f0ad5887..bf1743f90 160000
--- a/Submodules/agg-sharp
+++ b/Submodules/agg-sharp
@@ -1 +1 @@
-Subproject commit 1f0ad588760ac4629fd8f7844ec985087173b037
+Subproject commit bf1743f908241e19886562ba9752944763417896