Filament Clip
This is available on printables as Claw Clip with Label
After my problem with a filament tangle, I looked at a lot of filament clips on printables and found this one which appealed to me.
However, now having my MMU3, I wanted to label the clip with the kind of filament, so I spent some time picking dimensions off the CLAW and rebuilding the model in OpenSCAD so I could then make two models. One for the clip with a recess for text, and one for just the text. If I import the two stl files into PrusaSlicer with the MMU3 configured, it asks me if it should combine the files, and I can say "yes".
I can then assign one color to the clip and another to the text. Of course the print time goes from somewhere around 10 minutes to 40 minutes, but we must make sacrifices :-). The efficiency can be improved by printing more than one at a time since it uses the same number of filament changes no mater how many copies I print. An array of 10 clips takes 1 hour and 40 minutes instead of 400 minutes.
Currently printing two sets of 10 clips with two different color texts, it says it will take three and a half hours.
I'm unlikely to need many TPU or PC-CF clips (and I'm running out of colors), so just print four each.
All of these prints ran with no errors, so perhaps my MMU3 is fully dialed in now.