My hobby hovers around anything to do with technology, it keeps me busy. I design my own HW/SW when I feel I have the need for it. Otherwise I just buy and be done with it.
I been into from satellite hobby, cars, pc, microcontroller you name it. I apply what I know when theres a need for it.
I even built my own satellite receiver when I was a kid, this was from elektor magazine. As well as follow an instruction how to build a parabolic dish. But no Ill never do that now, satellite receiver can be had for free these days. Yes satellite hobby for me had died, I only install dish, flash firmware and just rewire it from time to time. Its hardly called a hobby now really.