It's an evolving technology. Give them time and 3D printing will be turning out anything you like in terms of firearm designs. Probably will be quite a while though before a $500 printer (with pennies in materials) could produce something the equivalent of a Sig Sauer. But it'll get there.
If nothing else, make a 3D printer cable of making a Glock frame and drop in some metal components and barrel. Maybe 3D print the metal frame work. I figure they won't be able to print things like springs and barrels, but there may be work arounds that still make it cheaper. I guess we are at the stage of the Libery Pistol at this point.
