Environmental-Castin'Craft Mold Builder. A natural liquid latex rubber used to make your own molds. Create highly detailed reusable molds. Can be used on models made of metal, clay, plaster, wood, plastic or glass. Brass or copper should first be coated with an acrylic lacquer or shellac. Seal porous materials, like clay, plaster and wood with a paste wax. This package contains one 16oz jar of castin'craft mold builder. Conforms to ASTM D 4236. Made in USA.