Summary I could not find anything on Thingiverse that fit my RobotDigg PLA spools so I made this 4 mm thick spool holder, quick print. With a small mod you could adapt it to fit any 200 mm diameter spools. Fits 21.93 mm diameter skate bearings, nice friction fit with a taper at the back to keep the bearing from being pushed into the spool. The Robot Digg spools Have a 38.14 mm diameter hole. 104 mm from center to base so fits the 200 mm diameter Robot Digg spool. The cross members are a tight fit so tapping them on with a small hammer and a drop of crazy glue makes a nice strong connection. Leave the little bag of desiccant in the spool so it doesn't back spool, the bearings are very smooth. I'm using a 6.26 mm bolt in the pic but it is sized for 7.75 mm threaded rod. Instructions Print it, tap the cross supports on, put a drop of crazy glue at the connection. Press in the bearings, put them in the reel and thread a bolt or section of threaded rod with a couple washers through the whole thing. Leave the little bag of desiccant inside the spool so it doesn't back spool.