This is a spool roller that attaches to a Lulzbot power supply. http://www.lulzbot.com/en/71-12vdc-20a-240w-power-supply.html It's working well and easily adjustable for different sized spools. Should also work to hold two spools for a dual extruder setup.Print the STL two times and assemble with 8mm threaded rod 120mm or greater. I used the stock prusa z leadscrews(210mm)that are wide enough for two spools. Use 4 608 bearing. The ribs attach to the power supply with 6 M4x10mm screws. You can modify the SCAD file to fit different dimensions or to print better on your machine. The scad does depend on MCAD. https://github.com/elmom/MCAD/zipball/master