TL;DR: It’s on thingiverse

Been wanting a practical compass for a while. Criteria: quick to adjust, doesn’t move when set, light enough for drafting, rigid enough for scribing trim. I never could find a good one to buy, so I designed one.

It will hold a wide range of instruments and points. The point can be 2mm-5.5mm diameter, and the arm has clearance so you can use a nail without trimming the head off. It holds almost anything from small pencils to chunky markers, by rotating the clamp to one of three diameter settings.

If you want to carry it in a pocket, you can just tap the wedge out and flip the point so it doesn’t spear anything important:

I made a quick little fixture for grinding flats on the screws:

If you would like to print yourself one, you just need a flat-head M5 x 30mm screw (countersink is 90 degrees for the perfectionists), or #10 X 1.25”, with corresponding nut and washer. File/grind two flats on the head so it measures 6.5-7mm flat-to-flat. The model files are here. The compass is easier to use if you smooth the conical mating faces with sandpaper and scribble some graphite on them.

Email me if you want me to make you one.