I've designed this air duct for a 50mm radial fan on my GEEETech I3 Pro B after using XDr4g0nX's fan shroud for quite a while (thanks for the design!). However, I think my approach has several advantages: The base and the throat are much more slender. So it doesn't conceal so much of your prints and it does not hit the glass clamps. Its height is adjustable in the range of 3.5 mm which may help to avoid some obstacles. The ring has a lot more holes which are directed downwards itead of rather inwards. Thus it cools your printed part itead of the nozzle. The airflow is significantly stronger. I printed it in PETG. The included supports can easily be removed. Now there is a second veion that adds a mount for the BLTouch. However, I didn't test this one. It would be nice, if someone could post, if it fits or not. June 3 2017: Update of the BLTouch veion I moved the BLTouch mount 3mm to the outside as the screws for attaching the duct and the BLTouch came really close. I closed the 0.1mm gap between the BLTouch mount and the support structure as this caused printing in air.