Once the mould is finished, molten wax is poured into it and swished around until an even coating, usually about 3 mm thick, covers the inner surface of the mould. This is repeated until the desired thickness is reached. Another method is to fill the entire mould with molten wax and let it cool until a desired thickness has set on the surface of the mould. After this the rest of the wax is poured out again, the mould is turned upside down and the wax layer is left to cool and harden. With this method it is more difficult to control the overall thickness of the wax layer. This hollow wax copy of the original model is removed from the mould. The model-maker may reuse the mould to make multiple copies, limited only by the durability of the mould.