Old shop aids.

[Enzo]

Oh I love this old stuff

Check out this guy's stuff

https://stevenjohnson.com/cardboard/wheelcharts.htm

[J M Fahey]

Impressive!!!

VERY impressive, with the Jeepesen Flight Calculator being bthe most advanced of them all..

My Brother is a Commercial Pilot and swears by his, trusting it more than the electronic flight aids available on any small/medium plane (single/twin propeller powered).

Of course, not enough for commercial jets in operation by airlines, but then it still serves as backup or sanity check.

Those are basically a mix of circular slide ruler , datasheet charts in an easier to use form or in the simpler ones, chart tables (such as resistor color codes) put in a pocket, easy to check shape.

VERY clever and handy.

I still use my old circular slide ruler, mainly to find new parts values when what I ask is missing , such as: "so you donīt have .022 uF caps but .027? ... ok, instead of 22k resistors give me .... ummmm .... 18k ones" ... or whatever.
Instant resuts just in front of you, and "all together" , easier to pick suitable pairs.