You’re describing my job exactly. I work in a clinic that designs and fabricates custom equipment for people with disabilities. I have a shop fully equipped to do all kinds of operations on all kinds of materials, because we come up against so many unusual problems and circumstances and need to be able to respond creatively.
I rarely do exactly the same thing twice. One day I may be machining and welding some metal attachment for a wheelchair, the next day I may be turning a custom knob to fit someone’s hand exactly, or modifying a crib for a mom in a wheelchair.
I work in a team with physical therapists and rehab engineers during the evaluation of the client’s needs, but most of the design work and all of the fabrication is my baby.
Not only do I have the satisfaction of doing shop work (I’m sure you can relate), but nothing beats the thrill of delivering that finished piece and seeing someone’s life get suddenly easier.
Prosthetics/orthotics work is no doubt just as rewarding, but it does require a whole lot of specialized education. I got this job just by virtue of having good and varied fabrication skills. There aren’t a whole lot of places that do what we do here, but check out job postings categorized as “assistive technology” and you might turn up something similar.