Almost-Frictionless Filament Spool Holder for Replicator 2X

Here is my Almost-Frictionless Filament Spool Holder for the MakerBot Replicator 2x (and anything else which mounts spools the same way). It gives your printer a continuous, smooth feed of filament with no snags, friction hold-ups or other problems - which is great considering how weak the Replicator extruders' feed motors are. Having built one of these (and reprinted several parts because it failed in the middle) I tested it by using it to build another - and I didn't have to reprint anything t