Some of you may remember this "slide rule" style early spoke calculator.

This one dates from 1980, was sold by the British cycle goods vendor Ron Kitching, and is based on the "Sutherlands Handbook for Bicycle Mechanics" calcualtions. After the earlier thread referring to the various online spoke calculating tools (one of which I usually refer to), I decided to pull this out of my archives... and to my surprise it works just fine.

Will not measure down to 10ths or 100ths of a mm., but neither do my spokes.
Notice on the back side (photo 2) the names of the most common rims sold back then.

- Too much Retro fun!