It's nice to be able to keep spools over the top of a 3D printer but once you have multiple spools it can be a real pain to try and swap out a spool that's in the middle. Have multiple printers using the same closet/shower rod for holding spools? It gets even trickier.
This design enables the use of the closet/shower rod AND allows you to easily switch out a spool.
The spool of filament in the photos is from 3Dom USA: http://www.3domusa.com
Print at Standard (0.2mm) layer resolution, 50% infill, no supports.