Z Rotation Indicator for 8mm Rod - especially Prusa MK3

I want to observe how much work the mesh bed leveling has to do and it is hard to observe.
Originally I just sticked some tape on the Z-Axis, but for my new printer I wanted a more elegant solution. So I sketched this together. It is designed for a 8mm Rod and 9mm spacing between the Rods. As the Original Prusa MK3 has.

Edit: In contrast to my previous printer, the Prusa MK3 seems to have a very flat and parallel print surface, so this is quite boring. Nonetheless it fulfills its purpose as nearly no correctional movement can be observed.