A spool holder bracket I designed for Joel (3D Printing Nerd)'s shelfs, for his contest but also just to see if I could design something with Tinkercad. I don't have a 3D printer to try printing it on yet and I think its a bit big for most print beds but if you can find a way to print it, I think it would work pretty well. It should just slide over the boards on 2 shelves and then the spool should stay on and away from the rest of the bracket because of the cone shapes, hopefully I got the dimensions right so the spools will easily fit over the outer cone shape. I also tried to make it more robust than the brackets you hold the shelves up with since it would be moved around a lot more than those brackets and because of the movement, would likely break easier if not more robust.