I once completely built a computer from scraps, including an orange screen hercules mono monitor (and ISA graphics card), case held together with tape, 160mhz (yes!) 486-class CPU, 24mb (probably 16+4+4) RAM, NO hard disk (it ran 3.1 + MS Works off a Zipdisk... first booting DOS 6.22 off a floppy and calling the Zip drivers) or sound card (Windows internal-speaker driver FTW), a keyboard from 1987 and a "spare" mouse from school...
Then used it, along with a scrounged 9-pin dot matrix printer, for about a year to do my schoolwork on. Including stuff with pics from an early digital camera (£700, 1.3mpix, awful CCD) that mum borrowed from work...
Works wasn't so bad - it was a definite upgrade from Lotus Symphony that was on the 286 I nicked the monitor and keyboard from - but I'd have preferred Office 6 if it'd have fit on the Zipdisk. Win 3.1 turned out to be a bit picky about you swapping out its primary drive halfway through a session. It did also have a 2x CDROM drive - pretty much for playing music (headphone jack, volume and play-pause/fwd/back controls on the front!), but we didn't get a CD writer until later, and it's not a very good choice for running an OS from anyway.
Eventually improved it when my school (this was late 90s) chucked out some of their creakier 486 SX-25s and 386s and I was able to cart away a 170mb disk, SVGA monitor and ISA Trident card from the skip...
My geek cred has slipped a bit since, but I do occasionally involve myself in a bit of not-entirely-necessary (ie I could pay someone else to do it, or just buy a new item) kitbashing to save cash and keep myself sort of sharp. It's becoming more necessary thanks to my working as an AV/IT guy in a college whose funding is taking a nosedive... you have to get creative to keep things working. Like transplanting half the optical guts of a "not human servicable", ancient but still valuable data projector into another one of similar model because they're broken in different ways, then spending a couple hours using the force to try and get the R-G-B parts of the image vaguely aligned again.
There's also the little matter of my homemade experimental 1x 8cm disc VCD edition of Spirited Away. Yeah, it's almost watchable. If you use a 13" TV...
And I can geek away for hours on music encoding comparisons and the like (yay spectrograms) ... or working out how to re-gear my car or bike for better speed or efficiency (or both), though only the latter is likely to ever happen.
Mind you I failed a little recently vs an otherwise not so geeky colleague (granted, he is one of the network managers, but otherwise doesn't nerd it up). Someone brought in an NES for lunchtime fun. It seemed to die when we changed the cartridge from what had been sat in there for about 15 years. I figured out a rather brownian-motion way of getting it working involving shifting the cart about... he refined it into a much simpler and reliable manoeuvre...
