Abstract: A dual-chamber container is formed in an injection blow molding process. Two preforms are injection molded around respective core rods. The preforms and core rods are then moved to a blow mold, in which the preforms are molded to the confines of the mold. The blow mold has partial walls between the two cavities, which provide directional control over the preforms as the preform wall portions are blown against and contact welded to each other. The outer walls of the preforms, which must travel and stretch a greater amount than the inner walls, are formed thicker in the preform molding operation.