I send the wax model off to be cast in silver by a casting company. The process involves making a cast of the wax, then heating the cast until all the wax has melted out. This leaves a void in the shape of the original model. The cast is then entered into a vacuum chamber where molten metal is inserted into the cast which fills the void left by the wax model. This produces the initial cast.
Once cooled, a rubber mould is made of this initial cast so replicas can be made in wax, and the mould and initial cast is sent back to me.