As the gun debate continues in the U.S., one American company has created a blueprint to create gun parts using a 3D printer.<br/> <br />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.<br/> <br />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.<br/> <br />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.<br/> <br />The AR-15 information has already been downloaded more than 10,000 times since it was made available on February 25.<br/> <br />The founder of the company said the goal of release of the information is to "teach people prac
