Prusa i3 MK3 Low Profile & Smaller Diameter Spool Holder

Remix of https://www.thingiverse.com/thing:2783900 to work with smaller inner diameter spools.

I also added some hollow cylinders in the actual spool holder part to hopefully help with rigidity (seen in the last picture, the circles surrounding the large center hole).

**Warning if you downloaded before 2018-03-28**
Model before 2018-03-28 had a protrusion on the frame clip that would hit the extrusion head while printing very tall parts. See image attached to thing this was remixed from.