Hi Steve, so that looks like the same kind of problem you were mentioning earlier, and having things leak out past the trimming boundary or weird little holes right near the boundary usually means the boundary is mangled in some way, like it has loop-de-loops in its edges or there are gaps between different edges instead of edges meeting up end-to-end, stuff like that.

It probably has to do with the huge complexity of that one single surface, you may be running into some kind of recursion or refinement limit in the geometry kernel that prevents it from getting a good quality snug fit intersection curve on that type of thing.

I'll try to take a look and see if it is possible to get a good solid from what you've got or not.

But it could be possible that you might need to dial down the density of what you are generating from ZSurf somewhat.

- Michael