Spool Holder Base for Enclosure

Needed a spool holder for the top of my enclosure and most of the ones I found had either:
* single bearings on either side rather than a roller, forcing them to use a fixed spool width
* Two part base for either side, needing careful spacing and more nails when attaching to enclosure.

The single part base allows easy attachment to an enclosure roof, and the wide 140mm rollers from [IsmaelPR1’s design](https://www.thingiverse.com/thing:1768975) allow it to hold any spool size.

I printed off two sets of the nuts and tighten them against each other, rather than against the walls of the base. I found this to be better as it:
* Puts less/no stress on the base part.
* Allows hard tightening of the nuts so that they do not budge at all.
* allows the screw itself to spin easily as well.

If you plan on using printed bearings i recommend doing this, as the freely spinning screw gives another slip point and lets it spin nearly as smoothly as metal bearings.