At least one group, called Defense Distributed, is claiming to have created downloadable weapon parts that can be built using the increasingly popular new-generation of printer that utilizes plastics and other materials to create 3-D objects with moving parts. University of Texas law student Cody Wilson, the 24-year-old “Wiki Weapons” project leader, says the group last month test fired a semiautomatic AR-15 rifle — one of the weapon types used in the Connecticut elementary school massacre — which was built with some key parts created on a 3-D printer. The gun was fired six times before it broke.

Though no independent observer was there to verify the test, a short video clip showing the gun firing and breaking was posted to YouTube. Federal firearms regulators said they are aware of the technology’s gun-making potential, but do not believe an entire weapon has yet been made.