According to the “gunsmith”:
I got my dad to fold the receiver and weld on the mag well so I’d be all legal and such. It uses sten mags, has a modified AK FCG, a luger barrel with a ring in it from a barrel wrench (I got it free at a gunshow), a fixed extractor, and a section of arc welding electrode as a firing pin.
It cannot be unseen! Bleach for my eyes!