I'm working on a mechanical design to be printed in metal -- hinges and springs, mostly. I'd become convinced that printing moving parts in metal was impossible. But then, for the tenth time, I watched the "Shapeways 3D metal printing" video (here) and realized that at the end, a) the Moebius Ants model is printed as a single piece, and b) the ants remain free to run around the track. My intuition for the steel process is now in disarray. I had guessed that parts would remain separate after the initial printing, and perhaps even the sintering/curing step, but had thought that the bronze infiltration step would be certain to fuse any parts that were touching. Because the ants (again, in my head) were lifted out of the support material and put back in for infiltration, I believed they would almost certainly end up touching one another. Obviously, that didn't happen. So: why did the ants work in metal? What are the design principles for moving parts? Can we print separate parts with clearances of, say, 1mm, and have confidence that they won't fuse during the later production steps? Thanks for the guidance.