Platinum cure molding rubber silicone rtv is used for prototyping and the reproduction of parts. Silicone moulds can be constructed in many different forms depending on the shape of the part you are making. In this section we will outline how to create the easiest one part flat back mould. Silicone is the first choice of material when casting 3 dimentional shapes that contain undercuts as it exhibits excellent release properties, a high level of surface detail, very good chemical and high temperature resistance.