I wanted a solid beam compass which I could use to draw models of the solar system in my science class. I also wanted to be able to cut circles out using an exacto type knife. The beam compass options I found were not as beefy as I wanted.
There are two sizes; one fits most standard wooden meter sticks and yard sticks. The other is sized for 1x2, allowing you to make a compass as large as you want by purchasing or ripping down lumber. This can be useful for architectural projects like arches.
The hardware is #10-24 hardware, available at almost any home improvement store. I printed up knob handles to make adjustment easy. I used the knob customizer by Hank Cowdog (https://www.thingiverse.com/thing:664192).
For a pin, I cut the head off of a 3" common nail, then put it in my drill and sharpened it using a grinding stone in a Dremel tool.
I printed these with 30% infill, no supports.
When I use ABS, I use a brim, but with PLA I don't need it on my printer.
It can be beneficial to hot glue the captive nuts in place.