High performance cooling assembly

####This is a helix fan duct for a 40mm fan with a blower, designed to redirect, shape and straighten fan's flow with maximum efficiency.

>It is designed to be attached to Wanhao i3 v2.1 printing head with 2x 20mm M4 screws with conical cross heads, while the assembly itself is held together with stock M3 screws.
All threads in the holes print well enough with 0.2mm layer and match stock M3 screws.
The bottom most surface of this duct is designed to be at least 2mm from the print bed at minimum Z position.
I also designed appropriate supports, included in the model.

This is an evolution of [my](http://www.thingiverse.com/Gascat/about) [previous design](http://www.thingiverse.com/thing:2037058) with an addition of helix duct inspired by [DaveGun's](http://www.thingiverse.com/DaveGun/about) [Vortex Fan Shroud](http://www.thingiverse.com/thing:2044285). Like my previous design this one is a product of several CFD simulations.

The assembly consists of 3 parts:
- helix duct wit