The Liberator isn't so much an actual pistol, but more of a zip gun. Though The Liberator does fire bullets.
The Liberator has the size and accuracy of an improvised weapon (pictured below), but it is deadly.
It fires a small .380 caliber bullet. You can download files to make one on a 3D printer if you have one.
Luckily for the world, a 3D printer can cost as much as $10,000, so this won't exactly put a gun in the hand of anyone who wants one. But it is an impressive technological feat.