At one point I was pulled to work in the hospital's optometry clinic. They had one of the mills to design and make glasses in the back. Computer-controlled, very intricate, a room full of different kinds of special polymers. I had enough issues with the mill on our small scale of a couple dozen pairs per day so I can imagine commercial producers go through parts and inputs quickly. Shame it's not something that you can easily de-industrialise and turn into a localised production chain like food. Polycarbonate still has to come from refineries and those are still dependent on Houston having perfect weather while the climate dies.

edit: Also very fun work. Optometry and ophthalmology tech are good roles if you're looking for entry-level medical work without the pitfalls of CNA/EMT/psych. Lots of interesting machines, the anatomy and physiology of eyes is neat, the workload is the right mix of diversity and technical aptitude.