I was getting annoyed with changing spools, I tend to change colors often. I designed this to be easy to place, have the spools glide easily when in use and sit snugly when idle.

You'll need some spare 8mm rods, and 3-5mm set screws
Print one set of rollers for each roll, realistically this will be as long as are your rods. I just used some old ones I had that were slightly warped and unusable otherwise:)