The "Liberator" is a nearly fully 3D printed plastic single-shot handgun designed by Defense Distributed and whose designs were widely distributed over the internet. It is the first fully 3D printable gun capable of being fired without blowing up, though that depends on the materials it is created with.
The gun's design is not 100% printable though, with two metal components being a part of the design. One is a nail that acts as the firing pin and the other is a metal slug that would make the gun detectable to a metal detector, which would make the weapon abide to the Undetectable Firearms Act of 1998 in the US. Those parts may be replaced with other things though, particularly if someone wanted to reduce the weapon's detectable.
The weapon is named after the FP-45 Liberator, a crude metal single-shot pistol designed by the US during WWII to be distributed to resistance groups against the Axis. It was intended to be used as a psychological tool to lower enemy morale by dropping tons of these weapons behind enemy lines to arm citizens and resistance groups.
