Mount for enclosure roof or a shelf above printer. It is easily removed when not needed, but securely fixed when in use. On spoolholder arm there is place for 3mm heat insert to put 25mm locking screw to hold arm in place. For roller you can use Ender 3 spoolholder roller that has bearings in it, or print Anthonys version: https://www.printables.com/model/158734-ender-3-s1-secondary-spool-holder
The author marked this model as their own original creation.