I truly enjoy this type of exercise and agree with Marv that this is an excellent example (although he solved it in an hour or less). Mr. Pete on YT has a series similar with tools and some are still in limbo as to what they are.

I had a couple of pics that I can't find now of a device I found at the hardware store which also has surplus military stuff, mostly Swiss. It had a most beautifully made screw system for back and forth motion but had no clue what it did. I'll keep looking for the pics as no one at the store knew and all us old timers didn't have a clue either.