UPDATE (06.05.17) If the duct doesn't say in place you could try http://www.thingiverse.com/thing:2297996 . It fixes it to one of the fan screws.
Added step file for easier modification.

UPDATE (18.04.17) It has been noticed that in some cases air stream directed downwards will bounce off the bed and will come up towards the nozzle. In order compensate use 'regular fan speed at height' Cura option. Set it to something like 50 mm, so the fan speed will ramp up as the nozzle moves farther away from the bed. Leave your experiences int he comments.

UPDATE (10.04.17) An updated model (version 4) that clears the heater block is uploaded. There is now a cutout that should accommodate the corners of the heater block, in addition, I moved the whole structure 1mm down, it still still hangs ~2mm above the tip of the hotend nozzle, shouldn't get in contact with the print.

This is yet another fan duct for a Anet printers. This is inspired by http://www.thingiverse.com/thing:1620630 but not quite a remix. After I've i finalized the idea i discovered quite many similar things and concepts.

Why is mine better?

• The biggest advantage is the targeted air flow, the whole structure hangs ~2 mm above the tip of the extruder nozzle but the air flow has a 'focal point' ~2mm below it. So rather then splashing cold air all over the hotend, the air flows to extruded plastic and the part below. This means that your hotend heater is not working against your cooling fan, better hotend temperature control and less current consumption (a win-win)
• Internal surfaces are optimized for airflow and smaller 'internal resistance', you can probably run your fan at 50% without loss of cooling efficiency
• The cross section of the doughnut is much bigger then cross section of the air outlet, the air pressure is roughly similar in all points of the doughnut. This means that airflow from all outlets is also similar. The extruded plastic is cooled evenly from all sides.
• There are 4 guides that show the direction of the airflow
• It looks good (even if i say so myself)