This is a fine approach too. Just be aware that most modern mcu would be a hell to mount on DIY. Also, this works on literally any paper with super bold print setting.

I would recommend trying copper-based etch, it's easier to work with than FeCl3 (it's transparent, to begin with, and not as corrosive to other stuff). Edit: remember to wear goggles, all these things really destroy eyes on splash. Wash eyes for at least 15 minutes with running water if got it there.

Also, I've heard some dudes made really nice stencils for paste with some cheap hobby blade CNC tools on cardboard, there are models that have orders of mad higher precision than advertized. Never tried this myself though, lazer cut stainless steel plates from factory are just soooo good (and also a source of high quality steel in a workshop when you don't need them anymore, they make perfect wood scrapers and such)

I'm not sure which how-to's you've come across, but my wanderings led me to this guy, who seems to have a very comprehensive video.