I have used 3D printers quite a bit at work.
You are going to have 4 basic issues:
1) the material printed is pretty weak plastic on the affordable machines. You are not printing Glocks. You are printing something much weaker. Not sure if it is weak due to printing, or just the material properties. It works great for prototyping and even testing low strength products. Slightly better materials can be printed out of the $100k+ machines.
2) You only have material strength in one plane. Across the layers, it is super weak. This is because you only have the bonded strength across the grain.
3) Surface finish is pretty rough. I tried to make calipers once, but i had to handwork a lot to make them slide or read right!
4) You $10000 plus to buy the most basic machine. You need $100's for each print cartridge. Last, the one I kept going need service every 3 months.
I think I could have printed AR mags that would work, maybe a lower. No way I'm printing a working 1911 or Glock. You could probably design some shotgun pressure zip gun that uses 410 shotshells at reduced pressure. Zip guns are probably easier to make with common plumbing materials!
Last edited by Nathan; February 25, 2013 at 06:17 AM.