E3Dv6 Bowden X-carriage Mount v2 Circular Fan Duct

This is a remix of the E3Dv6 Bowden X-carriage mount v2 for Prusa i3 with a less noisy circular fan duct design (head cooler v4) by Bunjatec and principe_polo (http://www.thingiverse.com/thing:1698475). The redesigned extended mounts are included in the download.

There are several benefits of using this carriage with this fan duct, namely:

- Smaller extruder mount allows for better access to the available volume on bed
- Quieter than other mods
- Single fan source means cooling and power