Meet The 'Liberator': Test-Firing The World's First Fully 3D-Printed Gun

[TampaAnimusVortex]

15. One doesnt need hardened metal...

Assuming were dealing with a criminal who wants a weapon to rob a bank or some multi-fire short term operations...

Standard quality steel water pipe is sufficient as long as its surrounded by plastic hard and strong enough to keep it together - which if the creator here is already using it to fire rounds currently with plastic only... obviously it is. The problem he has now is the heat, which would still build up in normal pipe. It would be less accurate than a normal pistol obviously, but given most pistols are short range weapons anyways, it shouldn't be that big of a deal.

Your just guessing on the idea that other parts would need to be reinforced... but even assuming the area right behind the bullet needed some metal, one could see a slight modification involving metal washers handling that pretty easily.