A mixup of Mikolaszuza's Extruder Rotation Vizualizer. I felt the need to have a "Crash Test Dummy Marker" variant of the extruder indicator. Or, as Google teached me, a so called Fiducial Marker.
The scientific look of this makes the printer 23.7% more awsome! :)
Link to original, with all the info you need.
See how scientific it looks! :)