[belval]

For me the next step should explore how to cut out the firing part of the process altogether, pottery looks cool but the process requires a lot of energy. Perhaps it could be done on a piece of wood planed by hand? You can get those fairly flat. Then use copper tape (or laminate your own copper really) with some homemade adhesive?

Actually now that I think about it you could just make pine rosin (pine resin + alcohol) as your adhesive. For the copper laminate this might be harder without steel rollers or a way to cut.

[analog31]

Amusing historical note, that's where the word "breadboard" came from. Wooden cutting boards were readily available, and people would make circuits by screwing down tube sockets and other components.

[pjc50]

Dredged from memory is the "phenolic" circuit board, popular before about 1990.

https://picamfg.com/pcb-base-materials/ "FR-2: Phenolic Resin with Paper Reinforcement" / https://epra.eu/en/sustainability/bio-sourced-and-bio-based-... - you could make an entirely natural-derived paper+resin circuit board, with high dimensional stability, and validated by real use.

The only downside is it's not inherently fire resistant.

[jna_sh]

For what it’s worth, these can be fired in a campfire! No kiln or anything necessary.