As above.
I guess bowyering isn't a formally recognised trade as such in most places (although there is probably a guild in the UK?), so anyone who makes bows, and wants to call themselves a bowyer, can; there's various adjectives that may qualify a bowyer: amateur, professional, hobbyist, expert, master, hack; there's probably various other trades and professions which would enhance the credibility of a bowyer - cabinet or furniture making, engineering etc.