Small profile spool holder for the MK3S, MK3S+ with 608 bearings for smooth rolling. Sides have a retainer to prevent spools from jostling around, and the outer edges have a very slight raised line to reduce surface contact and friction against the spool. Curves clear the MK3S+ at maximum Z. Spool holder is strong, with no perceived flexing using 1kg spools, and grips well to the frame without slop. The design has less vibration and slop than other rolling spool holders I've liked, and the dimensions/fillet curves allow easier removal and repositioning than some of the others. The spool sits as far forward as possible without hitting the extruder at max height, which helps smooth out the filament path feeding into the extruder when most of the spool has been consumed. There is also a channel to allow wires from any LED lighting to pass through.
Each half fits together, and can be simply glued, or use 3x M3x20 screws with matching M3 nuts. You'll also need 4x 608 bearings, also known as skateboard bearings. Fit is very precise, but there is variance between frame dimensions so tightness onto the frame may vary. The tolerance onto the frame was tuned to be grippy but not too tight to be able to reposition for different spool widths.
The design is very forgiving with print settings, but I used .2mm layer height, 4 perimeters for clean prints and strength, and 15% rectilinear infill. I've also used default .2 settings with no problems. PLA was perfectly fine; PETG will undoubtedly work too. No supports. Gcode is for PLA and 4 perimeters. The spool holder has 4 pieces total, and it is small enough that all 4 fit onto the MK3s bed easily for a single print.
One of my first Fusion 360 projects, so feedback is welcome for improvement. I couldn't find a holder I liked that was minimalist in design, sturdy, and small, using bearings, so hence one of my first projects in Fusion.
If you want the gcode or .3mf files, they're available at the PrusaPrinters link here: https://www.prusaprinters.org/prints/54833-minimalist-low-profile-bearing-spool-holder-for-mk