Fits to Prusa i3 from MakerFarm (Greg's extruder with J-head). Modelled in Wings3D. Inspired by many other circular tubes here :-)Both parts are to be printed without support. The frame can be printed with any settings, but make sure it's not too brittle. The tube must be printed with small layer thickness (I used 0.15 mm), otherwise the 45º slope will not print well. There are small support "bricks" in the outlet slit, they are only for printing and have to be removed later with a sharp knife. Connect the fan, tube and frame with three small woodscrews. After that, attach the frame to the extruder with another three woodscrews (you will probably have to drill three holes in the extruder).