I'm using milimeters. The parts and assemblies are VERY small, so I'm not shocked that parts aren't printable; the little details are right at the ragged edge of what is printable. I've been revising the design to get it printable over the past month. What's odd is that parts of the design simply vanish. This doesn't happen when converted into a STL from Geomagic, just MOI, which made me wonder if it was an MOI issue.