Actually getting coins of the same composition, and weight requires a lot of effort. First you have to create an planchet of uniform thickness and then cut blanks of uniform size. It is not clear than hydraulic presses were in use at the beginning of the story arc, which implies man pressing (human operated screw presses - although i suppose animal muscle power through gears could be implemented).
I've ignored the fineness of the precious metal, and the control of the alloying process - I suppose the rms fineness could be insured, but intra-coin variation could be interesting. Then there is the creation of the dies, the lifetime the dies, not to mention the collaring and centering process. Until very recent time US coinage had interesting variations in pressing caused by technical (and human) issues.
Just saying minting a coin can be difficult, and highly technical job.