Re: How noisy are the cooling fans? @Jake
My slipstick is a Faber Castell log-log slide rule. I would like to say that it is the same one that was bought for me in 1971 when I went to senior school, but that got lost in one of many house moves, and I had to do a like-for-like replacement from eBay.
Although I think I still know how to use all of the scales (it's got around 20 different ones), I don't do the type of maths that it's best suited for very often.
I have one of my Grandfather's slide rules, probably dating back to the 1930's that he would have used at the RAE in Farnborough (it was one of the UKs primary aircraft research institutions). It's engraved polished ivory on wooden slides, but feels so fragile that I don't play with it very much.
When it comes to abacuses, not me. I used a blackboard and chalk and counting gates when counting sheep and hay bales on my father-in-law's farm before he retired.