Howdy,
Generally speaking, there are no rules governing bringing out-of-game items, either crafted in-game during an event, or at home, and selling them for in-game coin, out-of-game coin, or both. Plot, as a rules, does not keep track of such items, which renders the value of such items entirely up to the parties involved. If you think your pewter goblet is worth 5 silver and someone agrees to pay you that much, more power to you.
Where it gets dicey, in my personal opinion, is that because such items are not accompanied by an in-game tag, Plot and our rules team must treat them as items of no economic worth. Without a tag, such items cannot be stolen or, within the context of the game, forced to be returned. If, say, you sold five pouches for a total of 20 gold, and then were attacked and robbed of that 20 gold, even if it were by the person you just sold them to, neither the plot team nor our rules marshals would or even could enforce a requirement in-game or out-of-game that the pouches be returned to you.
Items that you bring in to game would also not be usable at logistics to pay for any in-game tagged production you might want to create. If you did want to make them so usable, then you would need to have your item stamped with an enforcable value, which could be done by paying for the enforcable value to logistics and having them assign an "evaluation number" to the object. On the flip side, per the rules, that makes such an item stealable within the game, and you'd have no out-of-game recourse should your items be robbed from you at some point (and, if you died while on a mod, for example, you'd be forced to give them up as lost treasure).
So, ultimately, it's up to you and what other players will agree to. Some players have done this sort of thing, bringing in handcrafted items that they brewed, smithed or worked leather for, and sold them for in-game coin of varying degrees, or simply provided drinks that they bought from Costco to sell in-game. From a rules and plot perspective, we are generally very hands-off about such interactions, because the system neither explicitly supports nor disallows such.
