A offset for each side of 1.5mm from Juangv's 0.1 fan duct. Gives a larger gap between heatblock and fanducts (where the air comes out), so it wont touch the heatblock.
Use rafts for better quality! Makes the fan duct look better and the fans fitt easelier without cleaning.
May need to scale it up a bit for better easier fitting of fans.(1% scaleup or 101% off original size did it for me.) Do this in X, Y and Z.