This is a simple adapter to connect build a spool out of standard European 50mm plastic sewage pipe and some 608 skate bearings. Both the bearings and the pipe are press fit when printed on our Thing-O-Matic. I used a M8 bolt through the bearing as an axle.
It doesn't really work, the diameter is too small for the loose plastic filament. When pulled the strand under tension cuts through the stack of filaments and ends up at the bottom. Presumably re-spoling might help, need to test it. Also need to make another version for larger diameter pipe. That said, this system beats our old system of storing the filament in a box on the table.. :-)
This part was made with Tinkercad. Edit the part online at: https://tinkercad.com/p/acc032818bbe0f42
Print out 2 pieces of the coupler. Press fit the 608 skate bearings. Tighten the M8 bolt and nut, the bolt head should be on the side of the bearing with the end sticking out. Press fit the coupler to the sewage pipe, add some glue to hold it in place. Add sides guides made from cardboard. Hang above your printer using wire or string.