"Wilson's latest radically libertarian project is a PC-connected milling machine he calls the Ghost Gunner. Like any computer-numerically-controlled (or CNC) mill, the one-foot-cubed black box uses a drill bit mounted on a head that moves in three dimensions to automatically carve digitally-modelled shapes into polymer, wood or aluminium. But this CNC mill, sold by Wilson's organisation known as Defense Distributed for $1,200 (£740), is designed to create one object in particular: the component of an AR-15 rifle known as its lower receiver."