I made a spool holder to hold the original PVC tube supplied with the printed to hold 2/3-ish spools on top of my printer.
It goes really well with my Filament Guide, they fit snugly together on the top part between the LCD and the Z Top mount;
I used a 35% infill to make sure the parts were a bit stronger because it would have to hold up ~2Kg of filament at some point.
2 outer perimeters, 2 bottom and 3 top layers are used in this print.
It took about 1h15m per arm to print.
I took the measurements of the PVC tube and looked/asked around what standard sizes for spools are.
Using this info I designed the spool holder so that the filament has some elevation from the LCD screen but does not have to much wiggle on top of the printer.