One of the world's finest modeling materials, Roma Plastilina is the renowned choice of professional sculptors. An oil-based, non-hardening modeling compound, Roma Plastilina is permanently pliable and works smoothly. It's available in four consistencies: Soft, used for making large sculptures. Medium, generally used for portrait heads, busts, and figure work. Medium-Firm, used in making models and smaller objects; Extra-Hard, used in highly detailed work.