Ball bearing support for Makerbot filament rolls on Replicator 2/2X

This is a variant on my previous filament roll holder; see http://www.thingiverse.com/thing:42595 for images. It suits the standard Makerboot spool - which is the size on which Aussie filament is now also delivered.

A great performer if you want low friction spooling...

Uses standard roller-blade ball bearings; 22mm OD, 8mm ID, 7mm thickness...

**[January 2015] Added 56mm roll-width version for a closer fit on some new spools**