The production of a plastic molded part utilizes a barrier layer embedded in plastic. Plastic is injection-molded successively in different cavities of the injection mold onto a three-dimensional preform made from a cut of a multi-layer barrier film, which multi-layer barrier film comprises a barrier layer coated with plastic on both sides. The plastic coating of the barrier film cut is at least superficially melted by the injected plastic melt. And the preform is supported by a support formed on the corresponding partial mold on the respective opposite side.