The electroforming of hard nickel dies for the injection moulding of reflex lenses was pioneered by Rotoplas and are produced from master dies known as pin bundles. The bundles are constructed from a number of stainless steel pins, clamped together in a stainless steel frame and custom built to specified requirements, incorporating compensation for the effect of light refraction. Each individual pin is ground,lapped and polished to form a cube at the operative end and the reflective efficiency of the resultant lens depends primarily on the extreme accuracy and finish to optical standards of this operation. Although hexagonal pins still predominant we can offer a variation in pin shape and size to meet customers requirements. Each cube optic reproduced by electroforming is an exact copy of the individual pin and therefore retains the perfect cube formation on the moulding, even when the pins are set over a curved profile. Where such contours are required, CNC information is necessary to allow setting plates to be machined.In the course of designing the pin bundles, datums are created relative to the car lines,so that the electroformed dies can be wire eroded or ground and then CNC machined on the back face to suit the mould base.