I liked Tom's idea of using an indicator that more accurately shows which filament is currently loaded.
In order to visually adapt it to the MMU3, a two-color pointer is required.
In my case the base color is black with a white arrow.
So I adjusted its pointer accordingly.
Not only the colored arrow, but also the slanted corners on the top complete the overall picture.
No glue is necessary to attach the indicator to the selector. It is held in place by friction.
Simply attach it and you're done.
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The author remixed this model.
Model revised:
optically adjusted upper corners,
Arrow individually so that you can print it in a different color.