I really liked the convenience on having the filament attached to the top of the printer so I decided for my first design to make a filament holder to attach to the top of my machine. I designed the lower arm first and used a 1/2" piece of aluminum tubing for the cross bar. This first arm holds 3 rolls. Then I got more colors of filament and thought I could modify my original holder a little to make a second holder. I also made a connecting arm to stabilize the whole thing. I think it works really nice and can hold up to 6 rolls of 1 lb filament(the smaller rolls). Right now I have 5 rolls on because one of them is a 2.2 lb roll.