I build an Uv exposure box out of an old scanner i got for free, and one of those small facial solariums with 4 small UV tubes in it, i found for next to nothing in a flea market.
I used some photosensitive spray called Positiv 20 to make my own photosensitive PCB’s.
But getting everything right is a freaking nightmare. The coat of spray has to be right, the exposure time, the development too.
I usually have it working, but about 1 in 6-7 times i screw up someting
My entire analog synth is made from boards made that way.
But for small simple boards i prefer to use the laserprinter toner transfer, it’s just so much easier, but requires access to a laser printer of course.