A question for today

A guy in my office ordered a bunch of parts (case, CPU, fan, etc.) to build a new computer and several other people are standing around talking about it. It got me musing about what the equivalent of the "build-your-own-computer" hardware geekery would have been in the past, specifically the 1920s and 1930s. In other words, what would these people have been "geeking out about" building or working on in yesteryear? My initial thought (coming from the SF and historical background that I do) was radios and such, ala Popular Mechanics and the Gernsback magazines. But then it occured to me that this might be less of a "pure geek" kind of thing and more "obsessive mainstream," which would lead (in the '20s and '30s) to automobiles and gearheads, ala the original Gasoline Alley, etc. (And yeah, I'm doing this quickly at work, while it's fresh in my mind, so you'll have to google all those references for yourself, I'm afraid.)

I'm not sure. What do you, the readers at home, think?