When I saw Cube's Mega Extruder Rotation Visualizer Bundle: https://www.prusaprinters.org/prints/152587-mega-extruder-rotation-visualizer-bundle 

I thought it was pretty impressive. But there was something missing. So, I designed a more “Hexy” version. Because, as you probably know, Prusa favorite shape, from all I've seen, is a hex. 

Other parts:

Glue

8X3mm Neodymium magnets 

Visualizer 

Instructions:

Apply the glue to the visualizer (Note: the hole is just for reference) then press the magnet into the glue. Let the glue dry for a minute or two. Then attach the visualizer to the motor with the magnets.