@everytownofficial: 3D-printed firearms are the new frontier of ghost guns. Mia Tretta — who was 15 when she was shot and wounded by a classmate armed with a ghost gun that was built from a kit ordered online — explains why 3D-printed firearms are becoming increasingly common. California just passed a groundbreaking bill to block 3D printers from printing guns. Governor Gavin Newsom let’s get it done.