a method of producing a molded article includes the steps of positioning an insert within a first mold , and filling the first mold with a low melt allow to form a lost core assembly . the lost core assembly includes an external shape corresponding to the desired cavity formed within the molded article . the inserts are supported within the lost core and form a part of the surface of the cavity of the completed molded article . the lost core assembly is over - molded with a thermoplastic or thermoset material . the alloy material is removed leaving the inserts within the molded article to form specific portions of the cavity .