PrePrap Prusa i3 fan nozzle cooling

I seen various design fan nozzles here, but they was not an acceptable solution for this or that reason, or have some disadvantages. The one of main reason is, that I have chinese knock-off of Prusa i3 printer. Found on ebay for 200 Euros as dyi set. I know, I know... don't beat me. But despite some disadvantages and flaws, working well. Better than I thought. For the price I paid, definitely can't complaint.

So let's look why I reject other designs:
- too low airflow
- too complicated
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