a method and apparatus for injection blow molding hollow plastic articles characterized by increased capacity due to back - to - back operations or stack molding and a rapid and efficient operating cycle . the process and apparatus includes back - to - back injection mold stations , back - to - back blow mold stations located on each side of and adjacent said injection mold stations in side - by - side relationship therewith , back - to - back ejection stations located adjacent each of said blow mold stations in side - by - side relationship , and blow cores cooperating with said injection stations and blow stations , wherein the operation of said cores is facilitated by an overlapping cycle .