Hi Martin,

re:
> I've been helping out a prospective purchaser of MoI and he seems to have found a bug when revolving a closed profile.

Currently the profile to revolve can only have one coinicdent line of contact with the revolve axis.

A case like this with 2 lines in contact would need to generate a solid with a void region inside of it. Revolve doesn't know how to make that kind of result currently.

To get the desired result, you'll instead need to have 2 separate profile curves like this:



Then when those are revolved that will make 2 solids. Then boolean difference can be used with the inner solid as the cutting object to make a single solid with an internal cavity.

- Michael