Abstract: A wax pattern mold and molding process are disclosed for forming a wax pattern of a hollow, thin walled object, in particular, a golf club head. A mold is provided in at least two halves defining a mold cavity. A core made up of a plurality of interfitted parts is placed in the mold to precisely define the thin walls. The core and mold are provided with a registration channel such that the core is properly registered in the cavity to ensure dimensional integrity of the thin walls. Pins, holes, slots, and fingers are provided to lock the core parts together while the wax pattern is formed and to permit the core parts to be disassembled through an opening in the mold without separating the mold halves.