I'm assuming your son isn't 39 years old.

What a way we travel in life. In the "old days" I built my first crystal set radio complete with cat's whisker at age 11, followed 10 or 12 more and more elaborate crystal sets, winding up with 4 different external antennae for different stations and a switching mechanism to combine/isolate them. The last which wasn't a kit was a two-transistor radio at age 14 so as to have a reliable way to tell time backpacking. Couldn't afford a watch which could endure a kid owner.

(Years later I build a crystal set to show my daughters it could be done. Being young teenagers they were politely awed except for the middle daughter, who was amazed and infatuated. She wandered around with earphones on constantly, playing with that thing for 2 solid weeks.)

I built my first computer 2 years ago. Similar to the one your son did. I wonder what he will be building when he's 66??!!

Congratulations to him. And you.

Arf