I made one but it extended below the extruder and I could not level the build plate.
My original one is melted but Makerbot sent me another one. Mark do you know why the original design has a protrusion but does not allow the air to come out toward the nozzel? Sharon Did you get my email?
I had a similar problem with my attempt to make this part as well. My first effort melted. The second just seemed to be to thick. Not quite as bad as this image but it was less than 1mm between the bottom and the end of the nozzle. I went back to my original one. :(
That's a shame, I guess that the combination of tolerances between the extruder tip and the fan mount are such that I have more room between the heater block and the tip than you do. I assume that you have pushed the fan duct up as high as it will go before tightening the screws? It can touch the Kapton tape as there is a ceramic insulator between it and the heated element. My extruder tip is approx 2 mm lower than the bottom edge of the duct, yours looks to be about 1mm above. You need some clearance as the duct will knock things off the build platform it it's too low.