Hi Steve, so I can confirm that the boolean union on your eagle-gray03.3dm does not work right and generates some messed up trimming boundaries. But unfortunately I'm not sure what I can really do about it - it does seem to be related to the extreme complexity of that one single surface.

Really NURBS surface processing is not particularly designed to work on things like that, stuff of that nature usually tends to be more in the domain of polygon modeling.

I think that it's hitting some kind of recursion or processing limit, and also when I tried to do some other alternative techniques like using surface trimming operations instead of booleans I ran into a lot of issues with excessively long processing time and running out of memory while trying to do those operations.

So I don't really know how to best help you with this - possibly your best bet would be to generate a somewhat lighter density surface out of ZSurf and see if that helps things work better or not. Other than that, you may be looking at using a totally different program like a polygon mesh modeling program to do that kind of work rather than MoI.

- Michael