3FPD-Replicator 2X - Extruder Upgrade - REV3

This is an extruder upgrade designed specifically for the Replicator 2X similar to whpthomas, and others, but with improvements.
-base is fully printable without supports(REV3=DESIGN TWEAKS)
-arm is printable with only external supports (bearing slot)
-arm integrates feed tube mount as well(REV3=DESIGN TWEAKS)
-tension spring geometry improved (REV3=MORE TENSION)
-use 5/32" and 1/4" bits for tight clearance bearing/arm pivot holes
-uses Makerbot hardware kit for Rep2 + 1 e