The screw head replaces the original rotating handle. This size solves the problem of showing the handle in panoramic photos with panoramic head and a fisheye lens.
There are two sizes, one for an M8 threaded rod and an M5 size (used in other things but it's the same design).
I'm attaching the Freecad files and the STL, which I used to design the part.
The nut size is a little tight because I like to melt them into the plastic.
I printed the part in ABS with 100% infill, but less infill will do the same thing since it is not to thick.
I would add some supports bfore printing to to the holes correctly.