Method of manufacture of identical parts displaying different indicia

摘要

A method of manufacturing plastic parts which are otherwise identical but which display different indicia such as typewriter keys which comprises the steps of injection molding a plurality of identical parts of a plastic having a filler material capable of undergoing a color change and thereafter exposing individually the identical parts to a radiation source for changing the color of localized portions of the part to display the indicia while retaining the molded color of remaining portions wherein the plastic is polyacetal and the filler is carbon black or graphite.