Five plaster copies of Ancient Chinese cast iron implement moulds.

Castings are made in many ways, for example sand casting, where a wooden pattern of the required shape is used to make a mould of sand, into which the molten metal is poured and allowed to solidify. An advantage of this method is that complex shapes can be produced but, however, the mould is destroyed once casting is complete and a new mould has to be made for each casting. Where a given object is to be made in large numbers, for example tools or implements, a permanent mould is used.