You know what would be *really* cool? A 3-D printer that could work in optical-quality glass. I'm gonna go code myself up a Noctilux! In Contax mount!

...OK, I suppose that's a little ways off still. But I can think of lots of things that should be easy enough to print up in plastics with reasonable levels of precision: film holders, lensboards, mounting flanges, adapters. They won't have the durability of metal, nor the precision of professional machine-shop products, but in many settings that would be fine; certainly better than having a camera go into forced retirement because of an irreplaceable part.