Small spool holder adjustable with magnets

I love how the [thing:93652](http://www.thingiverse.com/thing:93652) is a great, simple, flexible and very low-drag spool holder. I had been using it for a while just next to the printer, until recently, when I decided to move the spool of filament within the printer's enclosure, since there is enough space for it on my XYZ Da Vinci 1.0.

At just about the same time I bought some new filaments, and these came with spools of smaller width than I had before, so I thought of a quick and frictionless way to adjust the position of the rollers to match the varying size of the spools. Since my printer's floor is metallic, I figured that the best solution would be -guess what- *Yeah Bitch! Magnets!*

So this remix adds holes to attach 4 round magnets of 14mm diameter to the rollers. I used some pretty powerful ones that I had lying around and they provide a really strong fix. The roller definitely won't move unless I want it to!

Additionally, some of the new spools came pretty full, li