The coin design is cut directly into tool steel using a computer-controlled engraving machine, creating what is known as a reduction punch. This process takes up to 24 hours. The reduction punch contains a positive (raised or relief) impression of the complete design of the coin.
The reduction punch is placed in an hydraulic press. In a process known as hobbing, the design is transferred onto a softened steel block, using 100 to 400 tonnes of pressure. The result is a master die, containing a negative impression of the coin design. The master die is hardened, and is then used to hob another steel block. The result is a working hob, containing a positive impression of the design.
The third and last case of hobbing occurs when the working hob is hardened, and used to create the production die, which has a negative impression of the design. The production die is used to strike blanks, turning them into coins.
Proof coin dies get additional treatments so that they can transfer a high level of detail to the finished coins.