Still have my dad’s pre-WWII with ivory scales in velvet lined wooden case.
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!)
I have the same one that my recently deceased Dad used pre-WWII.