Bolt-on Lightweight Ducted fan-MakerGear M2 (& silent build recs)

This fan shroud for Makergear M2 allows for a boost in cooling at the point of extrusion, resulting in higher quality prints and steeper overhangs without support. Alternatively, it boosts a quieter and lower output fan's performance to near-or-better than the stock cooling fan.

Can be bolted on stock printer with a few fasteners (see below).
~~**Edit 10-26-2015: Woops, this might only work for people with 40x40x20mm extruder fans. A version for stock 40x40x10mm extruder fans will be publish