To mint the coin, slab of the metal is required. There were many way to produce this slab, but in case of gold or silver coin, the weight is equal to the value, each coin must be the same weight. Therefore, the moulds of same size were previously prepared and casted the metal. On the other hand, since the bronze coin needed not accurate weight, it was casted in cylindrical shape and cutted by a saw.

For striking the coin, two moulds, made of iron or bronze, were usually required. The one for the obvious side was fixed to an anvil and the other for reverse side was fixed to a punch. The slab was heaten before the striking to copy the design clearly. It was placed on the anvil and the punch was set on it, then striked by a hammer. So the designs were copied on either sides at same time.

It is said that the mould was able to be used over 10,000 times. If it was broken, new mould was made, though the another pair was still used continuously. The coins have same design only one side were essencial materials for the chronology. Sometimes the coins were recycled, we can find the faint trace of old design under the new one.