:) There are many (it's a thing):

https://hackaday.io/projects?tag=CPU (Some are FPGA, most are TTL) Including two risc-v implementations (one seems stalled):

https://hackaday.io/project/18491-worlds-first-32bit-homebre... (No activity for a while now) and https://www.youtube.com/playlist?list=PLEeZWGE3PwbansoxKjjMK...

One I am particularly interested in is the Gigatron:

https://hackaday.io/search?term=Gigatron&category=project%20... (Especially now that there's real IO being hacked in)