Layer fan duct for E3Dv6+BLTouch

This is a fan duct for being used with a layer fan in my Geeetech Prusa i3, converted to Bowden. It's meant to be used with [this](https://www.thingiverse.com/thing:2670180) carriage mount. Everything is measured to be compatible with a BLTouch sensor, mounted with [this](https://www.thingiverse.com/thing:1221968) clamp.

Using a layer fan severely improves things like bridges. One of the photos attached shows a comparison of a bridge torture test before (black) and after (green) adding a layer fan.

I did it in ABS (red photos) because that's what I had available at the moment, but it should work equally fine in PLA, since it's designed so not any part comes near heating block nor heatsink. In fact some of the photos show a black PLA version I printed while testing the design.

Design was made with Onshape, it can be downloaded/exported/edited in [this link](https://cad.onshape.com/documents/944cb2deecceb806080212ba/w/ce1cfd6690d9bd5975b9d251/e/a5834578473202bc6e732eb7).