This enclosure requires no additional hardware. If you print from gcode / 3MF file, there is filament change command added to swap colors. You can print in two or three colors. This works even if you don't own the MMU! You will just have to change the filament manually when prompted.

The knobs are designed to have 1.75mm filament pressed into them, to create the vertical marking. I suggest placing a bit of filament on a flat surface and pressing the knob onto it, rather than trying to push the filament in. If needed, the filament can be glued in - mine snapped in nicely.