WARNING!!! Since I designed this and have been running printers for several years with a couple recent near miss fire incidents, I've done a lot of thinking about fire safety. IT IS A REALLY BAD IDEA TO STORE FILAMENT ABOVE YOUR PRINTER. It's kind of like storing a bottle of gasoline above your kitchen stove. If your hotend happens to catch fire, it will almost certainly spread to the reel of fuel directly above it and then the rest of your house/office. Instead, put a fire detector or auto extinguisher directly above the printer and put the spool a distance away so if there is an incident you have some time to put it out while the fire is still small.

I built this stand to hold filament reels on top of my Mini Kossel. The spool uses standard 608 skate bearings to create an effortless unwinding by the extruder.