As the gun debate continues in the U.S., one American company has created a blueprint to create gun parts using a 3D printer. A group called Defense Distributed has released instructions that anyone can download that explains how to use a 3D printer to make an AR-15... the part of a semi-automatic rifle that ordinarily requires legal permission to own. 3D printers use a process called additive manufacturing to make objects from a digital model by laying down layers of material. Today's affordable 3D printers are used to make simple items like keychains and Legos. In the wake of the Newtown Connecticut elementary shooting in which 20 children were gunned down, anti-gun violence advocates say the prospect of duplicating a lethal weapon is alarming. The AR-15 information has already been downloaded more than 10,000 times since it was made available on February 25. The founder of the company said the goal of release of the information is to "teach people practical anarchy."