Hi Martin, so yeah you do have self-intersection in that case after performing the sweep. Sorry, I was not able to understand what kind of self intersection you were referring to in the previous 2D only image.

I think it's pretty unlikely that something like that is going to be feasible to automatically clean up.

I guess though that the self intersection in your case here ends up trying to form pretty much a cylinder surface on the outside, if you want a result like that you would probably be looking at something like only sweeping the inside surfaces and having just a solid cylinder surface as the outer piece rather than a self-intersecting sweep that ends up filling up the same area as a cylinder.

- Michael