set of parts for hole diameters M2-M6 threads. starting with a standard tap drill diameter in the middle adding and subtracting .1, .2, .3 to the diameter.
the intention is the parts can test the specific diameter that works with your printer, your settings, and your filament. Many cases a standard machine screw works as good as any other. The big advantage is it is the easily available screw. There are other screws that can be better.