Compact Cantileaner Wall Mount Spool Holder

I wanted to mount a spool on the wall without it sticking out, and all of the designs I could find had the third wheel at the top of the spool. I wanted something more minimal, less complex, and using less material.

My design puts the hook wheel in the spool hub. This does limit the compatible types of spool, one could make the same design with adjustment, but would have had to give up my other goals. I only have polymaker spools, I can only say it works with polymaker spools

Designed assuming 0.4mm perimeters.

But Wait There's Less! (read before printing)

I have not had the time to put towards actually making a good reverse bowden mount, in fact the design I have right now is so bad that I haven't included the worst part, the part that mounts the bowden tube. If you want to print this yourself you are going to have to solve this problem. 

My first try used a fixed mount tangent to the spool, this had enormous drag and basically didn't work at all. The design shown in the photos is a marginally viable hack. I like the semicircular piece, but the clip on post is weak, and the clippy thing almost doesn't work at all (so you can't have it). 

I'm posting this unfinished 30% hoping somebody else has brain to spare and will make a really great solution to this, 70% to shame myself into finishing it.

Here's the overall design of the rail clip:

Bill of Material

• Approximately 50g of some filament (including supports)
• 4x screws that can be made to go through a 5mm hole and will secure the mount to the wall you have.
• 1x 608 bearing
• 2x ??? POM V-Grove bearings that I had
  • 5mm shaft
  • 24mm OD
  • 11mm thick
  • 6mm groove width
    It's not important for them to be v-grooves, but they do need to be grooved or the spool will fall off. U-groves might actually be preferable. As long as you can mount them with an M5 and they have similar dimensions, it should work out
• 3~4x M5 heatset inserts (1 for the bowden post)