Hi Rogurt,

> Now I cleaned up these areas. Unfortunately still offset/shell
> wont work (tried 0,2 + flip)...

Are you using MoI v1 or the MoI v2 beta?

I loaded your newest file shell_04-2.3dm that you attached into the latest v2 beta, and I am able to generate an offset of 0.2 units.

But there are still some problem areas with those side pieces.

The offset looks like this:



This seems to be due to a messy area right near the corner of one that surface, if you look closely you can see some irregular shading here:



That likely means that the surface is not well formed in that area, it actually has a tiny spot where the surface is actually folded back on top of itself, so the surface normal actually changes a lot in that little area.

It looks like that surface may have been created such that they are tangent to one another at the corner rather than forming a distinct corner? It can be better to avoid creating surfaces that are configured that way and instead build a larger surface and trim it.

With something complex like this, you may just want to model the inner or outer surface more directly by lofting/sweeping/whatever it as well instead of trying to offset it.

Offset is especially sensitive to areas where there are self-intersections, folding or overlapping, or tight bends in the surfaces. You need to have more simplified and regularity in the shapes for it to really have a chance.

- Michael