Abstract: This is a molding apparatus designed to mold a plastic tub of circular transverse cross-section and re-entrant shape. Specifically, the tub tapers from its closed bottom to its opened top. The mold core is, therefore, collapsed radially to permit extraction of the plastic tub from the mold. This radial collapse is accomplished by forming the mold core of a central segment and a plurality of peripheral segments, and then axially extending the central segment while moving the peripheral segments along a radially inward path so that core collapse occurs. The exterior shape of the peripheral core segments defines a circular cross-sectional shape for the interior of the tub, despite the fact that the central core segment has the configuration of a hexagonal pyramid. Side mold segments which move radially outwardly and a tub extraction ram complete the equipment for extracting the tub from the mold.