Switches come in various forms, but most are small Lego-like plastic blocks, about 1 inch square, that can be easily manufactured on a 3D printer and go for around $200.
Law enforcement officials say the devices are turning up with greater frequency at crime scenes, often wielded by teens who have come to see them as a status symbol that provides a competitive advantage. The proliferation of switches also has coincided with broader accessibility of so-called ghost guns, untraceable firearms that can be made with components purchased online or made with 3D printers.
