In an attempt to help the young, inexperienced manufacturers, the town will buy (every month) tack from your shops if that tack is in a shape so poor that nobody is likely to buy it.
Since the town is low on coins, it will ignore the items that have a price set too high. It will pay you more than you would get in the market, but it will not make you rich.
So if you want some extra coins, put tack for sale, but remember to ask for a fair price, or else nobody will take it. In short, this means that the town will pay you at most double what you would get in the market for that item.
We are only buying tack with the shape below 30%, and only a limited number of each type. That means that the town will not buy everything you manufacture.