In search of DIY-able #PCB substrate. Have amounts of scrap copper.
Thought about electroless copper plated plywood even.
Just for lulz tried (and failed) to make toy stuffing+PVA composite (won't cure without air). That was my debute in tech parody genre
For proper FR4 can't find an open design of a fiberglass weaver. (need to make one?)
Target characteristics need just to be enough for RepRap-level electronics (mm range trackwidths and separations and enduring a low temperature soldering session).