Rob: I tried Netfabb cloud and interestingly enough, it removed the inner shell, so the model is not hollow anymore, back to square one
stonysmith:
Thanks a lot, I had not realized it was possible to do these basic cuts in the free version of Nettfab studio.
So I went ahead and cut the bottom. I made sure to uncheck the "triangulate cuts" option otherwise Netfabb adds the bottom again.
It's not a perfect solution, because I would have preferred to keep the side walls and remove only the flat bottom by booling out a cylinder, but I can accept this compromise!
So I get a cut mesh (see first image below). And of course, it needs to be repaired. The problem is that when I repair it, Netfabb retriangulates the mesh and builds the bottom again (see 2nd image below). Any idea how to prevent Netfabb from doing this? I guess I need to execute individual repair actions, not the automatic repair, but which actions?