A simple plate to hold reference bolts and nuts. Since I find these to be less expensive than actual taps and dies (at least for the more common sizes), I like to use a metal bolt for cleaning up printed nuts and a metal nut for cleaning up printed bolts.
Having one of each close at hand makes it easy to clean printed threads. The holes in the center are sized to allow for a bolt of the specified size to just fit through. The lower set of numbers are the thread pitch for the specific coarse metric bolt size.
The center holes are also handy for hanging on a hook.
I've generally printed with 0.2mm layer heights, although 0.28 seems to work OK also. I've tested with and without supports, and depending on your printer's tuning without can be fine.
I set a pause at the beginning of the numbers layer and manually switch filaments then.
The author marked this model as their own original creation.