Has anyone else looked at the Wiki Weapon Project from Defense Distributed? 3D printers + guns = http://defensedistributed.com/
The better technology is still coming. Printing in plastic is nice and cute, but you can currently print in metal if you have enough money for the printer. Technology will progress to be printing in titanium before to long.
I think they actually have a 3D printer that can do Titanium Alloy. Its used in the auto industry mainly. But as you said, Im sure in a few years we will be amazed at the new innovations in 3d printing.
You are right about costs. The member on ARF was discussing the ridiculous costs of material when making the prototypes. It would cost 10+ times what a forged lower could be bought for.
There was a mention of one shot disposable guns that were undetectable by xray. That was the part that was upsetting people.