diff --git a/MatterControlLib/DesignTools/EditorTools/ScaleControls/ScaleDiameterControl.cs b/MatterControlLib/DesignTools/EditorTools/ScaleControls/ScaleDiameterControl.cs
index 3d3afe0a6..fdeac8896 100644
--- a/MatterControlLib/DesignTools/EditorTools/ScaleControls/ScaleDiameterControl.cs
+++ b/MatterControlLib/DesignTools/EditorTools/ScaleControls/ScaleDiameterControl.cs
@@ -185,10 +185,16 @@ namespace MatterHackers.Plugins.EditorTools
 
 		private Matrix4X4 GetRingTransform()
 		{
-			Vector3 newBottomCenter = ObjectSpace.GetCenterPosition(RootSelection, placement);
-			var rotation = Matrix4X4.CreateRotation(new Quaternion(RootSelection.Matrix));
-			var translation = Matrix4X4.CreateTranslation(newBottomCenter);
-			return rotation * translation;
+			var rootSelection = RootSelection;
+			if (rootSelection != null)
+			{
+				Vector3 newBottomCenter = ObjectSpace.GetCenterPosition(RootSelection, placement);
+				var rotation = Matrix4X4.CreateRotation(new Quaternion(RootSelection.Matrix));
+				var translation = Matrix4X4.CreateTranslation(newBottomCenter);
+				return rotation * translation;
+			}
+
+			return Matrix4X4.Identity;
 		}
 
 		public override void Draw(DrawGlContentEventArgs e)
diff --git a/MatterControlLib/DesignTools/Operations/FindSliceObject3D.cs b/MatterControlLib/DesignTools/Operations/FindSliceObject3D.cs
index 3cab8d9cc..4058af75b 100644
--- a/MatterControlLib/DesignTools/Operations/FindSliceObject3D.cs
+++ b/MatterControlLib/DesignTools/Operations/FindSliceObject3D.cs
@@ -73,7 +73,7 @@ namespace MatterHackers.MatterControl.DesignTools
 			// remove every face above the cut plane
 			RemoveFacesAboveCut(mesh);
 
-			slice.Vertices().TriangulateFaces(null, mesh, SliceHeight);
+			slice.AsVertices().TriangulateFaces(null, mesh, SliceHeight);
 
 			mesh.Transform(itemMatrix.Inverted);
 
diff --git a/MatterControlLib/DesignTools/Operations/PlaneCutObject3D.cs b/MatterControlLib/DesignTools/Operations/PlaneCutObject3D.cs
index 91e756c03..bb94d8812 100644
--- a/MatterControlLib/DesignTools/Operations/PlaneCutObject3D.cs
+++ b/MatterControlLib/DesignTools/Operations/PlaneCutObject3D.cs
@@ -76,7 +76,7 @@ namespace MatterHackers.MatterControl.DesignTools
 			// remove every face above the cut plane
 			RemoveFacesAboveCut(mesh);
 
-			slice.Vertices().TriangulateFaces(null, mesh, cutHeight);
+			slice.AsVertices().TriangulateFaces(null, mesh, cutHeight);
 
 			mesh.Transform(itemMatrix.Inverted);
 
diff --git a/Submodules/agg-sharp b/Submodules/agg-sharp
index 816644eda..0c179037e 160000
--- a/Submodules/agg-sharp
+++ b/Submodules/agg-sharp
@@ -1 +1 @@
-Subproject commit 816644eda817f2e36dd68e034ffa19eef6a5548b
+Subproject commit 0c179037e1e5cce65f01fc3f4d15ea923d1fc346