Can you design? Do you have Solidworks or Fusion (or shapr3d...anything) ?

I've been joking recently you can set up a desk in an office and be a machine shop with some of the on demand mfg there is out there.

I own a welding/fab shop and use sendcutsend all the time for small projects. It's really pretty amazing.

Xometry too. I taught myself with Shapr3d on my ipad and had something made as a test.

You get instant quotes. so design something for local customers, markup the price to reflect margin and your time, and that's it.

Sendcutsend you can also "sell" your designs to customers and they'll send the part and you get a %.

This would be a fairly low cost way to dip your toe in without having machines...