Take a rectangle cut from half a square and torture it via box-pleating:
and you get a nut that actually takes the thread of the bolt previously made with the same hexagonality, nice.
This was an odd fold, it looked like it was going to hell at every stage, the inside collapse looked like it could not work, until it just did. Tucking away all that paper inside to leave a relatively clean hex nut on the outside is paper engineering genius.
Folded from “Brilliant Origami” by David Brill (that is 3 Brill models in a row, time for a change perhaps?).