Spool Holder for 2040/V-Slot and Prusa i3 Bear upgrade

I was using @MartinMajewski's version of the spool holder for my Prusa i3 Mk2.5. After upgrading to the [Bear Full Upgrade](https://www.thingiverse.com/thing:2808408), I needed a spool holder that would fit 2040 aluminum extrusions. I ended up remixing this based on the MK3 version of Martin's design:
https://www.thingiverse.com/thing:1832235

It's held in place using M5X10 screws in the back and drop in T-Slot nuts (available here: https://www.thingiverse.com/thing:2544883)

Update 2019-