Since the first 3D-printed ... remaining small plastic piece functions perfectly as a "drop-in auto sear," a simple but precisely shaped rifle part that can convert a legal AR-15 into an illegal ...

A West Virginia man named Timothy Watson was arrested last week for allegedly selling a 3D-printed ... “drop-in auto sear,” a small piece of plastic that could turn the popular AR-15 rifle ...

The same 3D printers that can generate car parts and jewelry are also being used to create small plastic blocks that ... also known as switches or auto-sears. The switches – which prosecutors ...