Helix fan duct (customizable, parametric) for Anet A8 and the like

# Why

All fan ducts suck. This one sucks less (I hope!). There are several reasons: first, it does not restrict air flow (each branch cross-section is 1/2 of the inlet). Second, it maintains laminar air flow. Third, it provides even cooling from both sides (good for PLA plastic). Fourth: it's completely customizable, just load it into FreeCAD 0.16 and edit variables in cf spreadsheet.

Designed for Anet A8 (Hesine, Omni, etc), but you can change parameters to fit it almost anywhere.

# Us