---READ ALL OF THIS---
Use black PETG
I made a quick gcode to print. It should print fine but if you choose to slice it yourself, here are the instructions from prusa:
"RECOMMENDED PRINT SETTINGS:
0.2 mm layer height, infill 20% GRID and material PETG.
We recommend using black filament to print all MK3S and MK2.5S extruder parts. If you want different color, you can use it, but the FS-lever part should be definitely dark (black) and the other parts surrounding the IR-Sensor as well. In case you use any lighter colour for the FS-lever it might not trigger the sensor."
you can also fine the files for yourself here: https://www.prusa3d.com/prusa-i3-printable-parts/
"RECOMMENDED PRINT SETTINGS:
0.2 mm layer height, infill 20% GRID and material PETG.
We recommend using black filament to print all MK3S and MK2.5S extruder parts. If you want different color, you can use it, but the FS-lever part should be definitely dark (black) and the other parts surrounding the IR-Sensor as well. In case you use any lighter colour for the FS-lever it might not trigger the sensor."
The author hasn't provided the model origin yet.