It made a handgun using a 3D-printer, according to Andy Greenberg at Forbes, who was given early access to the process.
Defense Distributed calls its gun the "Liberator."
The gun is made of sixteen pieces each of which was "printed with a Stratasys Dimension SST printer in ABS plastic, with the exception of a single nail that’s used as a firing pin," Greenberg reports. (That just means it was printed with plastic, and a nail was added.)
He adds, "The gun is designed to fire standard handgun rounds, using interchangeable barrels for different calibers of ammunition."
Once Defense Distributed is done fully testing its homemade handgun, it's going to put the blueprints on the web so anyone can print out the design and make their own
Defense Distributed also inserts a strip of metal into the gun to make sure metal detectors pick it up.
But, as Greenberg points out the people that print out the design might not be inclined to put metal strips in their guns, thus making them much harder to detect.