FlexLoop - Flex Filament Loop extruder

This is optimized for Filaflex or another flexible filament like Nylon.
I also made some modifications to enable the use with the AJGW extruder set.

I made this version changing the excellent design by Audran, please checkout the original version at http://www.thingiverse.com/thing:169372

###Changes in detail:

1. Added filament guide at the extruder top *(AJGW compatibility)*
2. Filled the gap between the tractor screw and the filament hole *(Flexible filament mod)*
3. Down moved