Vault Tec calling! Equip your Prusa with this stylish Vault Tec Control Knob and be prepared for the Nuclear Apocalypse.
If you are printing at a 0.2mm layer height the change of colour is on layer 8.
The base for the knob was borrowed from: https://www.prusaprinters.org/prints/2839-millennium-falcon-prusa-control-knob
The author hasn't provided the model origin yet.