An interactive core memory electronic kit (core64.io)

cool now do delay lines!

"No, Mom! I wanted a Commodore 64 for my birthday, not a Core 64!"

Neat, although I really want something with 4096 bits for storing my ed25519 private key.

Cool. Next up, magnetic logic. This filled in the gap before transistors were became reliable.

https://en.wikipedia.org/wiki/Magnetic_logic

I played with this at VCFMW last week and it was truly delightful.