Hi Paul, well it's not really totally up to me - I get the shelling function from the geometry library that I license.

I have noticed that there are some particular bugs involving offsets of surfaces that have a "pole" point in them (where one surface edge is collapsed down to a single point) - that's the part that is going wrong in this case. So far most of the basic shelling problems I have seen seem to involve that particular bug. Hopefully if I can fix that one bug it should tune up basic shelling to work quite a bit better.

If you have shapes without those kinds of poles in them, you'll probably see basic shelling work pretty well.

I doubt that it will ever really get to the same level of sophistication as stuff like Pro/E or SolidWorks, but I'll probably be able to get basic stuff like your example here working better.

- Michael