They aren’t ‘grounds.’ You are freeze drying already-brewed coffee. The instant crystals are what is in the already brewed coffee, minus water. Adding water rehydrates the coffee.

Maybe electrical outlet testers. Things that could improve safety but are largely left sitting unused 99% of the time.

This could have security implications. I believe most libraries have a computer to use, not sure on permissions of using a usb stick.

Edit: I’m from US, so I am assuming Canadian libraries typically have a computer for public use.

Definitely look up a how to. It’s been 15 years since I did this, but you’ll need some photo paper to print the toner on, then use a towel and iron to transfer it to the copper clad cob. Then soak it in some FeCl for 15ish minutes. I just did this outside since it was so quick. Then like a small dremel with pcb sized bits works great for throughholes.