I created this simple but stylish holder that allows the filament to roll. It fits between the shelves (hopefully). It is only made from thin beams to allow for quick printing and prevent wasted plactic. Havent got a filament roll to test it sadly :-(

-Update- I have now added a new version that hangs on the edge of the shelf so that filament does not need to be moved. - again can't actually test it so pls let me know if it needs adjusting :-)

 P.S sorry for the terrible file names