Hi Marco, I looked into it some more, and the problem does seem to be that the geometry library that I'm using currently just assumes that the final result of the shell will have just one offset vertex to match each vertex of the original object.

That is the case for 3-sided corners like the corner of a box, or for things that are totally symmetrical but not for cases where many pieces of different angles touch at a single point like in your case - like I showed earlier in this case there should be 3 vertices created in that central area instead of one, even though the original shape has just one vertex in the center.

I have sent this example to the people who make the geometry library that I am using.

Hopefully they will be able to improve it to handle this case as well, I'll let you know what I hear back from them.

- Michael