reduced friction Spool Holder

Yet another spool holder.
Until now i used a spoolholder which snaps in the hole of the spool ( something like http://www.thingiverse.com/thing:767317).
As the two parts of the holder are connected by a threaded rod and two nuts, the bearings are pretty blocked.
Due to this i designed this small holder. It fits on a 20x20cm aluminium profile and takes 2 bearings (20mm outer diameter)
I used some bearings from inline skates as a 8mm threaded rods fits perfectly.

BOM:
2x spoolholder1.stl
4 bearings 20mm diameter
8mm threaded rod
20x20mm aluminium profile
spool holder which fits into the hole of spool