The problem isn't that the U.S. Army did this ...

The problem is that terrorists and ordinary outlaws will do it one day, too: The U.S. Army 3D-Printed a Grenade Launcher and Called it R.A.M.B.O.

All 3-D printed except for springs and fasteners. They even printed the grenades
(did not include the explosive filling).

Technology is wonderful - most of the time.