Patterns are made from wood, plastic or metal. Designs tend to be simpler but again complicated internal shapes can be achieved. Surface finish is usually very pitted.
Sand casting is cheapest technique to begin casting but does suffer from dimensional accuracy.
The patterns are packed in sand with a binder to give green strength. The patterns are removed and the two piece mould clamped together. Metal is poured into the cavity left by the patterns and allowed too cool. The sand is then knocked off the metal leaving the castings.
