Whilst I had been using Tech2C's E3D Prusa i3 mount, I was loosing about 15mm of Y-Travel, and I also didn't like the available fan duct options.
I've designed this mount with the ability to use (most) of the MK8 Extruder Anet A8 fan ducts (Semi-Circle, Full-Circle, Mistral etc) whilst still suiting a E3D v6. In addition being able to have more visibility to the nozzle to check on prints. This design also doesnt loose any build volume.
STL's also contain a bridge helper on the clamping holes for the E3D mount, run a 4mm Drill through to clear them out, or push through a 4mm bolt and clean up with a hobby knife.
I'm currently using Leo_N's Mistral 2.1, but other ducts should work fine.
Suits mounting to the Prusa i3 Rework X-Carriage (https://www.thingiverse.com/thing:119616) or similar 22.5mm Hole-Centre carriage
Settings for Marlin
define X_MIN_POS -14
define Y_MIN_POS -13
define X_PROBE_OFFSET_FROM_EXTRUDER 38 // X offset: -left +right [of the nozzle]
define Y_PROBE_OFFSET_FROM_EXTRUDER 6 // Y offset: -front +behind [the nozzle]