Dual Extruder Vulcanus V1.1

I designed a Dual Extruder for Vulcaman's excellent Vulcanus V1.1
http://www.thingiverse.com/thing:1130016

I was inspired by DemmaC's design http://www.thingiverse.com/thing:1254578

The distance between the 10mm smoothrods is 51mm.

I am very new to 3d printing so If you have any recommendations please comment so I can improve this design.

****Update March 22 2017****
I added another extruder bottom as per a request from another member.
Make sure which inductive sensor you ar