That's how mould look like:
Fig. 1 3D model of moulds
Fig.2 Prolab
At figure 2 you can see a prolab material used for milling on CNC machine to obtain female moulds. It has many advantages, the most important one is that the surface of mould is ready to use right after milling, so it saves a lot of time, unfortunately it is one of the most expensive materials available.
