Mechanical Math
I love simple mechanical devices. Being a computer nerd makes one appreciate simple things that just work, since most of our time is spent dealing with things that regularly and inexplicably don’t work.
Many years ago my dad gave me a slide rule that he used in school. I’ve not been able to find it, so I bought another one. It’s a KEUFFEL & ESSER something-or-other, because I can’t afford the Deci-Lon. I have no idea why, but it’s pretty cool though, eh?