Fully 3D Printable AR-15 Design Choice
DISCLAIMER: Hopefully I'm not crossing the line or going too far with the very legally questionable content, So always do this anonymously within the sanctidy of your own home.
As prepration for the apocalyptic civil war event, Also as a big shout out to Terrence Popp.
Tough elastic filament for the springs:
CarbonX CF+PEEK filament for the AR-15 parts: