The United Kingdom has restricted gun ownership since a 1996 massacre at a school in Scotland. When Defense Distributed released the instructions for their 3-D printed pistol, there was a new way for weapons to sneak past borders. Nevermind that the gun broke when both German and Australian police tested it, or that the gun itself can only fire a single shot of a small caliber bullet at a time; these guns are new, and they are a threat. Last night, police in Manchester recovered plastic printed parts in a raid. Except it looks like they found 3-D printer parts, not gun parts. Whoops.
This mistake, spotted at Gigaom, shows instead that police found a printer, not a gun. Manchester Police released two statements, one claiming that they seized parts of a 3-D printed gun, and a later, updated version revealing that instead they just found a 3-D printer. The raid was part of Challenger, an operation against organized crime. If the 3-D printer was in fact used for nefarious purposes, it's just as likely it was making counterfeit 3-D printers as it was making weapons.
For reference, here's what 3-D printed gun parts actually look like: