About 6 years ago I went to his Brooklyn apartment for his birthday. I had never heard of him, but he's distant cousins with my wife's step father and we lived nearby. We get to his apartment and I start looking at the book collection... a lot of interesting math and computer science.
I started talking with him 1 on 1 and at some point he drops that he created the first personal computer. I'm ashamed to admit it, but in the back of my mind I was thinking "oh boy, this guy's not all there." But then he took me to his office and there's a poster of him with the LINC and I'm realizing that I've hit the motherlode of awesome computing history from a primary source.
He then showed me his current project: a working model Broadway stage for his granddaughter. It had to-scale working versions of everything, including the lights and actual mechanisms for drawing the curtains. Then he fired up his Mac with a 30" monitor and showed me that every piece had been laser cut from schematics that he had designed. In raw postscript. The entire thing was programmatically generated from a massive postscript program that was fully parameterized so he could change the dimensions of anything single component and the whole stage would be regenerated.
That programmatic modeling project was a big motivation for the work I've been doing to make parameterized 3d models for ergonomic keyboards (https://github.com/adereth/dactyl-keyboard).
I definitely experienced some cognitive dissonance watching an 82 year old flying around vim editing postscript. It was a trip and it was really inspiring to see someone his age still hacking.