Cody Wilson makes digital files that let anyone 3-D print untraceable guns. The government tried to stop him. He sued—and won. Five years ago, 25-year-old radical libertarian Cody Wilson stood on a remote central Texas gun range and pulled the trigger on the world’s first fully 3-D-printed gun. When, to his relief, his plastic invention fired a .380-caliber bullet into a berm of dirt without jammi