Over many years, the following procedure has been evolved and makes good pins. The material is Carpenter’s 420 stainless steel drawn to a hex, hardened and ground. All steps and fixtures are shown. It has been found necessary to do only one pin in one groove. Any bunching up gave optical failure.
© 1974 Optical Society of America
Frank Cooke, "Making Stainless Steel Masters for Highway Reflectors," Appl. Opt. 13, 1010-1012 (1974)