Sliding Rail Filament Spool Roller

I was on a quest to keep improving my filament spool holders. Since I frequently change spools and almost every spool I have has a different width, I decided having something that could easily slide and adjust as opposed to discrete positions would be faster and easier. An added benefit of this is that the spool holders stay down and can't pop off if you use the holder arms. 

The bearings used are standard 608 bearings.

This spool holder has the following benefits:

• Sliding rail for adjusting to any width spool
• Holders won't pop off rails
• Rollers inside and outside pieces can accommodate a nut and bolt to hold it together
  (M3 nut and M3x12 bolt) - This is optional. They will force fit and hold on the bearing without the nut and bolt.
• Outside piece has a raised guide to keep the spool from coming off the side.
• Spool holder arms to keep the spool from being pulled off the rollers when the spools get lite or tangled. To be safe I usually use at least one with any spool I'm using.