Prusa i3 Dual Extruder Design

This is my take on a dual extruder setup for Prusa i3 machines.
It uses 2 E3D-V6 extruders, I use genuine ones (supporting British innovation) so you need to check sizes if clones are used.
It can be assembled as a side by side or a front and rear layout and includes optional 18mm Diameter capacitive Z-Probe mount and Filament Runout switch mount. It also has the option of either 3 or 4 linear bearings.
In both cases one of the extruders is adjustable.
Pros and Cons of different arrangements