The concept is really simple - you print 2 (or more) rails and 4 (or more) coasters. Attach the rails parallel to each other next to your printer (with double sided tape or with screws), assemble the coasters (keep in mind the 'jaws' of the coasters are not identical to give you better control on the position - rotate them 180 degrees to move them by half a tooth, also 608 bearings are required) then position the coasters on the rails accordingly to your spool dimensions and that's pretty much it. It was designed for PLA, I have no idea it it will work with other materials.