I decided my Prusa MK3s needed a really cool extruder visualizer - and decided to design an animated Rick and Morty Portal. Animated Gif of the visualizer in action.
Please see the Prusa Blog for details on building the inner, spinning, "swirl"
"Swirl" was printed in Inland PLA - Peak Green.
"Fixed Portal" was started with Inland PLA - Light Blue, and then changed to Inland PLA - Dark Green once the layer change was signaled. This allows for a really nice color version of the swirling portal.
The "Fixed Portal", when complete, will attach to the extruder housing directly. Then, using the previously mentioned Blog steps, the "Swirl" print was attached to a mini-magnet and connected to the extruder motor shaft.
The author hasn't provided the model origin yet.