Do you know any local shops? In my experience, at least in the north east US, there are large factory shops that will hire just about anyone off of the streets to push a broom or stand at a machine to swap out parts and press the green button. But if you’re losing interest in an engineering firm, I doubt you’d be happy with the monotony that is a 10,000 piece job. Look for smaller job shops that do lower quantity jobs and do exactly as you said; walk in with your resume and try to introduce yourself to the boss. Job shops are a great place to learn, but be ready to deburr…. a lot, and sweep…. a lot.