My wife has the desk littered with paper thumb tacks / push pins.
They’re copper or copper plated. Anyway a nifty idea for when you’re in a pinch and want to prototype a small low voltage circuit you can just use a bunch of these copper push pins and card board. However I wouldn’t use it for long-term. I myself if I can’t get a PCB I’ll leave it on the bread board or do a point-to-point setup for a long-term solution.