This will not fit the MK4 (yet).
As space is limited in my cabinet I created a low-profile version of the "Smoothest Rolling Spool Holder". A filament-guide is highly recommended to avoid the filament tugging against the upper frame.
2x 8*22*7mm bearings needed.
For MK3s in 60x60 IKEA Platsa cabinet. Enjoy!
I printed the main arm in 0.2 layer height with 23% infill and 3 perimeters, PLA. But PETG is probably preferred. Print the holder in same layer height or thinner. The press-fit slot may need some light sanding, the fit is tight.
To make the roller become the "smoothest rolling", scale the roller (spool_center) to 99% since I would say the fit for the spool roller is too tight on the bearings and holder at 100%. I printed it on a raft on its side with support at 0.2mm layer height using Prusament PETG Orange.
The author remixed this model.