In 2017, law enforcement agencies in the US recovered approximately 1,600 ghost guns, according to federal data. By 2022, that number had jumped to more than 25,000 — a nearly 1,500 percent increase.

Lego or MDF lattice were considered and abandoned as options early on. 3D printing at 100% infill might have worked, but because of the frame’s size, it would have to be assembled in pieces and ...