Ender 3 - Filament holder DELUXE (remix to use with 5/16" threaded bar with END EXTENSION)

Updated this on 9/30/2018 with a minor tweak to allow it to be used with the extension nut. Works the same as before and the extension nut is optional.

I remixed one part (mounting_bracket.stl) from Skrutt84's awesome "Filament Holder Deluxe" to allow using the following 5/16-18 x 6" threaded rod from Home Depot (which is about a buck and already pre-cut to 6"):

https://www.homedepot.com/p/Hillman-5-16-18-x-6-in-UNC-Steel-Threaded-Rod-881000/202242416

I have seen these rods in the past