No need for support, reduce the overhang speeds when printing it for the best finish.
Use a 10mm or 3/8 in. Elastic band to hold the line in place with the buck.
This spool stacks perfectly with this spool holder: https://www.printables.com/model/453123-fly-fishing-tippet-holder (thanks @Kazuchan_327910).
The author marked this model as their own original creation.