Exactly & that is what scares the political class silly & with 3D printing makes it even simpler for those who don’t have heavy duty machine tools in the basement. The STEN gun is a simple weapon but with 3D printing you can make parts for bigger & far more effective weapons.
I have (yet another) dumb question: Isn’t 3-d printing done with plastic beads?
How could plastic be strong enough to withstand the pressures for use in a firing mechanism?