GEEETech i3_fan_duct

this fan redirect system is a review on an existing project, my add is the channel that brings air also to the pipe before the the extruding chamber,in order to mantain it fresher and avoid filament melting in the channel. i also moved and re-designed the channel near the noozle and divide the two conducts with an asymmetric geometry in order to have more air to the noozle.