This cap simply slides onto the front LED of the speaker. I found that printing it in PETG completely blocked the light in comparison to PLA, which allowed some light to bleed through. The filament used in the photograph is Overture PETG in black and was tested on the matte black variant of the speakers.
The cap in the photo was printed on a MK4S with 0.15mm layer height and 100% infill.
The author marked this model as their own original creation.