This is a simple threaded rod and ball bearing spool holder. Adjist the bearing distance based on the spool size. Use one of the other rod holder designs to hold the threaded rod after placing the filament spool on the bearings. Adjust the spool holder distance to stop the spool from falling off the bearings. If the spool holder distance can not be adjusted, just print the two disks, and secure the disks with nuts on the threaded rod to keep the spool in place.