Slide rules are simple devices that can do some very complex mathematical calculations. They put into use some of the theory you learned about logarithms in high-school algebra.

The Slide Rule Museum has a template to make a model slide rule. I took that and transformed it into a piece of functional jewelry.

This will be made entirely from paper/cardstock. Advanced crafters can apply the same concept to wood and wood veneers, machined metals, or formed plastics.

Note that accuracy of the instrument is limited to the medium, construction method, and skill of the operator.