The crash likely happens because regionObj(0) is invalid or AddRegion didn't create a proper region. Make sure the lines form a closed, planar loop, and add a check to confirm regionObj(0) is not Nothing before extruding. Also, try using a small taper angle like 0.01 to avoid errors . Let me know if...

Absolutely, you're on the right track—and yes, you can use the Lookup parameter in dynamic blocks to show and hide various shapes, though it does come with a few limitations, especially depending on the AutoCAD version or vertical (like LT vs full AutoCAD) you're using.