Abstract: A process for inscription of parts from plastic material whose color can be changed through the effect of an energy radiation used for providing alphanumeric characters or other symbols on the key buttons of a keyboard. The office machine keyboard completely equipped with blank key buttons is for that purpose moved relative to the energy radiation, for instance a laser beam, with the coordinated character or symbol being inscribed on each key button by the energy radiation in accordance with stored data as the key button proceeds into the effective area of the energy radiation.