2 versions, one for the standard installation and one for a second spool in the right back or front left.
The original spool holder arm just has to be mirrored to fit.
Quickly made up in Tinkercad, feel free to modify yourself:
https://www.tinkercad.com/things/a3pGzcvvQz1
The author remixed this model.
Slot holder with the prusa spool holder connector on the back.
Angles are adapted to have filler upright after installing in Prusa Enclosure.