Kind of off-topic, but theoretically, it would be simple to make the migrant skills match the percentage of skills gained in your player fortresses.
I've never understood cheese maker reference .. because if any skill/profession is heavily overrepresented when I play it is fisher...
Wax Crafters. Basically Peasants.
How often do most players use metalcrafters? I find myself using most of my non-weapons grade metal on furniture, which falls under the blacksmith skill. There's nothing I need to mass produce that isn't better suited to other materials. Just the occasional chain, instrument, or minecart.
If I find a location with a lot of excess copper or lead, I'll make export crafts out of those materials, just to get rid of them.
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Depending on how eccentric he wants this to be, currencies were not always coins. Cowry shells and glass beads were also commonly used as currency. People joked about wool, but Viking Age Iceland did in fact use "Homespun" along with heads of cattle as currency. Vikings also used hack-silver, they would wear a bracelet made of silver and cut off a piece of it to trade for something. In D&D's Dark Sun campaign setting, where metal is ultra scarce, ceramics and gems are used as currency. Africa also used iron and brass to form
many different shapes for currency.
The modern notion of currency, that currency is backed by the power of the state, is a fairly modern concept (even younger than the USA is), and would be completely alien to most cultures around the 1399 tech cut-off. An improperly minted coin would absolutely still have its intrinsic value. I think the point of minting back then was more like a government certification that the coin was a particular weight of metal.