Abstract: A process for making a portion of a temporary mold capable of producing several prototype plastic parts, including using computer-aided design to produce a geometric computer model of a prototype part suitable for being molded in plastic, and using this computer model in a rapid prototyping system, such as a stereolithography system, to produce a mold portion from plastic material. The mold portion has an inner surface substantially complementary to an outer surface of the intended plastic part. Solid support is provided for the mold portion to prevent any flexing thereof in later operation. The mold portion inner surface is coated with a layer of metal such as nickel having a thickness of between 75 and 150 .mu.m, which layer has an inner surface adhered to the mold inner surface and an outer surface of the precise shape and dimensions for forming the plastic parts.