M5 Nut and Bolt designed to fit Radius gauge 1-20 mm by mibla.
Bolt has a tapered head and partially threaded to allow flush fit. 4mm hex key required to tighten.
I printed mine with a 0.12mm layer height and threads on with minimal resistance.
You may need to heat either the head of the model or hex key if it's too tight.
Will require your printer to be well tuned or go over the threads with a tap and die.
The author remixed this model.