Haven't done any yet.

I mean, right now I am still exploring ideas of what I can do with a
combined milling/electronics/embedded capability as a one person mail
order business.

I think there's plenty, so long as I do sufficient market research
while asking stupid questions on homebrew or metalworking.

I am learning that it wouldn't make sense to forge my own ingots. I
have thought of
a custom chassis system made of interlocking standard parts milled out
of reliable ingots made by someone else. I can elaborate privately.

Ironically, I have a potentially infinite source of cheap AL
sheetmetal, that wrecker I mentioned that people mentioned wasn't worth
donkey dung for making ingots of. I could explore things there. But I
really want to keep the few remaining $ that I have in reserve for elex
parts and software tools.

The Eternal Squire