In casting, a pattern is a replica of the object to be cast, used to prepare the cavity into which molten material will be poured during the casting process. Patterns used in sand casting may be made of wood, metal, plastics or other materials.Master pattern is the name given to a pattern having a double contraction or shrinkage allowance. ... The different types of material that can be used in the construction of master patterns are numerous. These types include wood, plaster, aluminum, brass, bronze, plexiglass, ren-shape, and more.