http://www.economist.com/news/united...ady-print-fire
Earlier this month they successfully tested a printed, plastic 30-round magazine for an AR-15, one of the most popular rifles in America. They called their magazine “Cuomo”, after New York’s governor, who championed legislation banning magazines that hold more than seven rounds. Others have successfully printed stocks, grips and triggers, though not the chamber or the barrel of a weapon. That is much harder; but all this tinkering makes many people nervous.



Some of that fear may be overblown. Making a gun for personal use is usually not illegal, and home-made guns are nothing new. Ginger Colburn, a spokeswoman for the Bureau of Alcohol, Tobacco and Firearms (ATF), says her agency has seen guns made from “pens, books, belts, clubs. You name it, people have turned it into firearms.” And it may lead to bad law. Michael Weinberg, a staff lawyer at Public Knowledge, an open-source advocacy group, fears clumsy regulation of 3D printing, rather than of the weapons themselves.