This bolt allows two different direction nuts at the same time. It makes an interesting fidget toy.

Print instructions

The bolt was made after seeing this video:
 

And while it's a lot nicer in metal, the 3d printed variant still is nice to play with. I printed with 3 perimeters and no infill except for the bolt head. See the 3mf file.
The 3mf has extrusion multiplier set to 0.98 for filament.

Print was done in Prusament Galaxy black in 0.2 mm layer height.
After printing the nuts need to be moved a couple of times and I applied a few drops of olive oil to make the nuts run smoother.

Clearance between the parts is 0.15mm