In the attached file I have a group of closed curves (ok a lot of them). When I extrude I get this caca.
Every boolean operation appears to fail with this “closed polysrf.”
I can extract the upper surface.
If I use CAP at this point I get a bad polysrf because some of the openings get closed.
What does work at this point is to do PLANARSRF using the red shape then joining.
I presume the problem is related too the number of closed curves extruded together.
Problem Extrude 1.3dm (6.1 MB)