So, this isn’t exactly retrocomputing and it looks like it’s from four years ago, but I just found it and thought that many here may find it interesting.
This guy built a simple 8-bit CPU out of essentially discrete logic circuits (from what I’ve see so far, nothing more complex than a 4-bit adder chip) and explained the entire process.
He built his first etching setup when in high school, after graduating college a few years ago, he ended up starting a company with Jim Keller, the coauthor of x86-64