Since Republic Metals is a U.S. based company most of the customers will likely be American buyers. So what about a patriotic theme. Patriotic themes tend to do well I believe.
Individual subjects on rounds of this theme-based series can be people who helped to shape this country (can include a Supreme Court Justice or two as just one example of many), places, ideas and values, and objects like the Liberty Bell as just one of many possible candidates.
The coins that tell a story are most interesting to me. There's plenty of riveting stories to be told in a patriotic themed series.
Patriotic theme is my suggestion.
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