Abstract: The present invention provides a method for manufacturing a mold to be used in creating cast polymer products such as cultured marble and cultured granite, particularly used as walls surrounding bathroom showers and bathtubs, but applicable to many other industries as well, using original natural stone materials to make the mold. The method of manufacturing the hardened mold resembling the appearance of natural stonework for use in constructing panels of molded cast polymer is comprised of arranging natural stonework material in a predetermined pattern and securing the natural stonework material to a backing to hold the stonework material in the predetermined pattern and applying material between a plurality of edges of the natural stonework material to simulate a texture to a plurality of stone gaps surrounding the natural stonework material. The method may additionally include the application of various layers of sealant, gel-coat, skim-coat, fiberglass, and resin.