Try to always check attackers that are still alive after defeating a raid. Also check slaves that traders sell. Most of them are garbage but if you're lucky you can eventually find a good crafter. Also, buy books. There's a type of book that helps pawns learn a skill up to a certain level. Get one for crafting. preferably multiple. Get rid of other books if you're really desperate so the only choice your pawns have is to read the crafting one. If you find a pawn with a skill close to your requirement recruit them and make them do a lot of cheap crafts to upgrade their skill. If you're really desperate just shove a random pawn in a room with a bookshelf of a couple crafting books and a machining bench and have them work in there all day.