While I applaud your treasure and the joy you have in keeping it, I have what I believe is the epitome of mechanical engineering, the Curta Calculator. Like the slide rule, it too was a victim of the electronic calculator. However, like the slide rule, there is nothing like the silky smooth action and tactile pleasure of using it instead of my iPhone (albeit much slower!)
Always admired those little coffee grinder Curtas. Just couldn’t justify the cost. I can only recall them being advertised in the 1960s Road and Track magazines for rallies.