On April 8, President Joe Biden requested that the Department of Justice (DOJ) issue a new rule banning the creation of so-called ghost guns as one of a handful of executive actions meant to curb gun violence following the recent mass shootings in Atlanta, Georgia, and Boulder, Colorado. Ghost guns are unregistered firearms that weren't assembled by licensed gun manufacturers or sold in highly regulated gun shops, and they're most closely associated with Cody Wilson, the founder of Defense Distributed. Wilson first drew attention as the creator of the Liberator, a functional plastic gun that could be manufactured at home using a 3D printer. Today, Defense Distributed's signature product is the Ghost Gunner, a do-it-yourself milling machine the size of small printer that enables anyone with enough time and interest to create unregistered firearms simply by purchasing parts online, downloading specs from an online library like Wilson's DEFCAD, and assembling the final product. Wilson says the units fly off the shelves every time a major politician so much as mentions gun control.