Update README.md

README.md

@@ -122,4 +122,5 @@ Horizontal slices of this surface are straight lines rotating at a constant rate
 The conservative method will give a nice connected straight line for every layer, but the full 3D voxelization is spiky.
 
 A similar situation occurs when making a hollow shapes using the thin boundary of each layer.
-This boundary only knows about the 2D horizontal slice so will not include enough blocks for a hole-less appearance from the outside.
+This boundary only knows about the 2D horizontal slice so will not include enough blocks for a hole-less appearance from the outside.
+The solution to this is using the 3D boundary algorithm, which is also aware of the layers above and below the current layer.