Since I want to operate my filament boxes with the MMU3 but without a buffer, I designed this insert.
I have only had my MMU3 on the MK4 for a short time.
But it printed the sheep with this setup without any problems.
The insert successfully prevented the filament from getting tangled when it was pushed back.
My intention was to keep the filament dry and to achieve the shortest possible filament path.
Edit: Obsolete New model with filament roller available
https://www.printables.com/de/model/1009131-filament-drybox-and-buffer-for-mmu
The author marked this model as their own original creation.