Plastic optics are often mass produced by injection, compression or injection-compression molding. Optical quality molds can be directly machined in appropriate materials (tool steels, electroless nickel layers, aluminum, etc.), but much greater cost efficiency can be achieved with electroformed mold inserts. Traditionally, electroforming of optical quality mold inserts has been carried out in nickel, a material much softer than tool steels which, when hardened to 45-50 Ilk usually exhibit high wear resistance and long service life (hundreds of thousands of impressions per mold). Despite their low hardness (<20 HR,), nickel molds are successfully used to injection or compression mold Fresnel lenses, retroreflective sheeting, conventional spheric and aspheric lenses, various diffractive surfaces, compact discs and other products. However, electroformed nickel inserts usually allow to mold only tens of thousands of impressions before they are scrapped due to wear or accidental damage. This drawback prevented their wider usage in general plastic and optical mold making.