Top and bottom ferrous carrier plates have a plurality of pairs of mating insert receptacles in full carrier plates and interlocked partial carrier plates. Pairs of mating nonferrous pre-molded inserts with mating mold cavities insert with a three axis floating fit into mating insert receptacles. Insert contact faces each comprising a flat surface portion having a plurality of mating alignment elements adapted for automatic precision alignment of the mating pair of pre-molded inserts. An injector structure comprising a plunger and pot bushing structure communicates with a pot on each top pre-molded insert. The bushing structure has a solidifying cavity and stripping structure so that retraction of the plunger separates the solidified material from the plunger face for automatic removal of surplus injected material after each molding cycle.