Plastics (and some metal) engraving is accomplished with the aid of a pantograph -- a scissors-like device with tracing stylus on one end and a cutting tip on the other .... It works something like a Le Roi set .... The operator guides the stylus by following or tracing within the grooves of brass "masters" (letters or designs), which causes the other end to cut or scratch the identical design, but not necessarily the same size into material fastened beneath it ....