Abstract: A mold system for a curable composite material. The mold receives the uncured plies of the composite material. A restraining member is attached to the mold to restrain a forcing member. The forcing member is positioned between the mold and the restraining member. At least a portion of the uncured plies are positioned between the mold and the forcing member. The forcing member is comprised of an elastomeric material having a high thermal coefficient of expansion. The assembly of plies, mold, forcing member and restraining member is placed in a furnace and heated. As the assembly is heated, the forcing member uniformly expands with increasing temperature. However, since the forcing member is constrained between the restraining member, whose purpose is to restrain the forcing member, the forcing member expands in a preselected direction determined by the shape of the mold, the forcing member, the composite part and the restraining member. The expansion however is limited by the mold.