Building a mini ternary computer can be a fascinating project. A ternary computer uses logic, which has three possible states (usually represented as -1, 0,, and +1) compared to the binary logic which has only two (0 and 1). While it's an unconventional approach compared to modern binary computers, it can be a great learning experience.
https://aitrot.com/building-a-mini-ternary-computer/my-project/