Ok, let me start off by dating myself - I started out building Heathkits back in the 60s and enjoyed building speaker systems as my first real project - I converted my closet doors to accept 2 12" full range Jensen speakers using my bedroom closet as the box.
HiFi? Perhaps, but Pink Floyd and Vanilla Fudge really sounded good - when my parents weren't home.
In college, I made my beer and date money by fixing stereos in the dorms for hung-over guys who couldn't remember if the party they threw was really that loud. Ultimately, I discovered a stereo shop that needed some help and ended up engineering and installing large-scale disco systems and home theater systems around the then-new Advent projection system and the really-cool BetaMax tape systems. At night, I built my own stuff from companies like Southwest Technical Products like the Tiger amps and the orgininal Leach amp. In those days, I got to work on many of the now-classic stuff like McIntosh MC-240s, Ampex and Magnecord tape decks, Thorens and Tandberg turntables, Klipsch, JBL and Altec speakers. What I wouldn't give for that old box of 300Bs we used to shoot BBs at that I used to remove from old Atwater Kent radios......
Then I got hooked on computers, which paid better and have been in that industry ever since. Most of my more recent DIY projects have been limited to mods to power amps and the like rather than ground-up things like I used to do - this more because of small children around the house. Still, I love my hobby of more than 30 years and have found new fun with the new digital DAC kits now appearing on the market.