One of the wild things to me is how incredibly elaborate chipmaking as become over the years. Per Wikipedia, the 6502's layout was made with "a very manual process done with color pencils and vellum paper". That's the processor that launched the personal computing revolution, powering the Apple II, Commodore PET and VIC-20, the Acorn, and the BBC Micro. Nearly 50 years later, things have gotten so fiendishly complex that "flip it over and put some stuff on the back" is a major industry change requiring who knows how many billions in R&D.