This year's first episode of CSI:New York featured a 3D printer that made a gun used to kill two people. The application of the technology in the episode was uneven. Here is my list of Yeas and Neas:
Yea: the gun was 3D printed from sintered metal
Yea: the 3D printer was a home-made rig
Nea: the gun's surface was perfectly smooth, as was the inside of the barrel
Nea: bullets fired from the gun left no stridation marks
Yea: the gun exploded during its second use
Yea: the CSI team found the files for printing the gun
Nea: the techie called the files "proprietary"
Yea: the CSI techie described 3D printing to his team by showing an apple that had been sliced horizontally many times
Nea: one of the CSI team said this concept was w-a-y to complicated for her
Nea: one of the team commented that creating a gun now was as easy as pressing "Command+P" (but the computers used were Windows, not Macs).