Put my hazmat gear on and tackled the most disgusting keyboard I've ever laid eyes on.
Full tear down. The keycaps all had a soak in warm water with a mixture of dish soap, flash, and bleach in it, and I agitated it fairly frequently. Upper casing I used fairy liquid and an old nailbrush. The cord I cleaned with windex on a microfibre.
Then I built this out of a couple of the machines I picked up, and some of the spare parts!
It has an AMD K6-2 3D 400 (at 416MHz because of jumper limitations, yay free overclock!)
A PC Chips M571, which despite the reputation PC Chips boards apparently have, is actually very good, and it has a modded BIOS to allow use of the K6 chips. (originally just for Pentium up to 233MHz I believe)
96MB of SIMM RAM
Guillemot Maxi Gamer Phoenix 3DFX Voodoo Banshee with 16MB of memory
A 6GB Quantum Fireball which is trying to burst my eardrums with its high pitched seek noises
And then just a TEAC 5.25", NEC 3.5", LG CD-ROM, AT PSU, and that black case.
Just finished installing W98SE on it.
The case had been messed about with to fit a janky ATX setup inside, so I have a hole in the back cover which was for a fan that I am going to plate and fill, and then I'll wrap the back cover black to hide it. Also had to take the power switch from one of the other AT cases because the one that was in there had been messed about with.