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.