This is my take on designing (in less than 3h, too, using Fusion 360 CAD) a spool holder that can fit onto two 3/4" thick wooden beams.
The "cross" ones fit between the two pieces (my idea is that a spool placed on top of it will keep it steady while the "single" ones fit only on the outer beam, being smaller and having a different grip. The "tag" versions have a little holder for a 1*1.5in paper card on which you can, e.g. write the name of the filament in use. All of them were created with minimalism in mind; in fact the 'rod' which holds the spool isn't a complete circle nor it is full on the inside (it should still be able to hold over 2kg of filament, as it's pretty big).
I took the freedom of inserting my logo and name on the very back side of these models, but they won't be visible once everything is setup.
I hope Joel likes my work but I'll be happy with as little as a mention in the winner video. I tried my best with this and I'm hoping it will capture 3DPN's attention.