Clever way to make screws that have no visible screw-head utilizing the tolerances possible with EDM machine tools.

Electrical Discharge Machining (EDM) tools are capable of machining part with tolerances of 40 millionths of an inch ( 0.00004″) (. 001 mm) and some up to 10 millionths of an inch (0.00001″). Effectively making seems between pieces practically invisible.