I've always thought the Gravity Spoolholder by @MichalFanta was a great idea, but I was content with my regular spool holder. Then I saw @Steven_36896's design and I thought it would be great to put that on the frame of my MK3S+ to save space.
I mirrored the Right side to get the Left side.
The author remixed this model.
This is built to snap onto the frame of Prusa MK3 models.