A system for manufacturing a shell for a batting helmet includes interchangeable mold-core portions configured to form a cavity for receiving molding material. The mold-core portions include a first base mold-core portion and a plurality of inner side mold-core portions configured to form an interior contour of the shell. The mold-core portions further include a second base mold-core portion and a plurality of outer mold-core portions configured to form an exterior contour of the shell. Mold-core portions are interchangeable, removable, and replaceable from an interlocked position relative to other mold-core portions. A method of manufacturing batting helmet shells includes selecting mold-core portions corresponding to various helmet shell configurations having various protective features, assembling the mold-core portions into a mold assembly, and providing molding material into a cavity in the mold assembly. A kit of parts for making a shell for a batting helmet includes a variety of interchangeable mold-core portions.