A method of forming reference flats on a plurality of styli comprises the step of placing the styli lengthwise in parallel grooves disposed adjacent the surface of a first plate, allowing the top portions of the styli to project above the surface. A coating of wax is applied to the flat surface of a second plate. The wax-coated second plate is then pressed against the surface of the first plate until the top portions of the styli are held firmly against the surface of the second plate, after which the second plate is lifted from the first plate with the styli remaining adhered to the second plate. The exposed portions of the styli are lapped to form the reference flats by moving an abrasive surface in a direction along the lengthwise orientation of the styli.