A rapid prototype tempering process comprises producing a rapid prototype part from a base material, creating voids in the rapid prototype part, and filling the voids with a filler material that changes at least one characteristic of the prototype part. The rapid prototype part may be made, for example, by stereolithography, selective laser sintering (SLS), extrusion, printhead technology, or the like. The base material is generally a brittle material and the filler material may be selected to enhance the durability of the prototype part, for example. Parts made completely from a filler material that is injected into cavities of molds made from a base material are also disclosed.