I built a mineral oil PC a couple of years ago. I epoxied the motherboard mount from an old computer case to some wood and then stuck the wood to the inside of

I built a mineral oil PC a couple of years ago. I epoxied the motherboard mount from an old computer case to some wood and then stuck the wood to the inside of a cheap fish tank. I installed the computer sans harddrive and then poured in 12 liters of mineral oil that I'd bought from a vet (Vet's use it as a horse laxative). It resulted in a perfectly silent system but because I didn't cover the top it was also a really effective fly trap. Within a few months there were a bunch of dead flies floating at the top of the tank. Also the weight made it a real effort to move around and no matter how careful I was there was always a mess when I needed to swap out or adjust a part. Still it was a lot of fun to build and I used it as my primary machine for about a year.