There a a few different techniques that can be used. Most of the lithography techniques use Hydrofluoric Acid, but if you are okay with slower build times you can etch the circuits directly with Ion beams or Electron Beams.
But the short story is you need an overhead projector, a microscope, and a few gnarly chemicals. Otherwise fairly straightforward.
Here is BreakingTaps fabricating home made chips, he has a fair bit of equipment though
https://youtu.be/RuVS7MsQk4Y?si=c8PH-FMfcfWLJLiG
There a a few different techniques that can be used. Most of the lithography techniques use Hydrofluoric Acid, but if you are okay with slower build times you can etch the circuits directly with Ion beams or Electron Beams.
But the short story is you need an overhead projector, a microscope, and a few gnarly chemicals. Otherwise fairly straightforward.