Casting is a sculpture technique that requires that the material be poured into a mold - think about an ice cube - water in a mold turns into ice that resembles the shape of that mold. The most common material used for casting is bronze, but any material that can be put into a predetermined mold can be used. The finished scupture can be solid or hollow. Those that are hollow typically use the "lost wax" method. Click here to see a video of the casting process.