Patterns are used to create the shape in the sand, into which molten metal will be poured to become the casting. Patterns can be made from metal, wood or plastic.
Most patterns are made from aluminum, called matchplates and have a long life before wearing out. Wooden patterns can be used provided the quantities are low and the wall thickness fairly substantial.
Pattern Makers also manufacture the core boxes required (see under Core Making). Shell core boxes can be made in cast iron, steel or aluminum. CO2 core boxes are made in aluminum or wood.
Patterns are not made in house, but are generally contracted out.