I wanted to try the original fan mount by creyc, but I had a remixed filament guide in place that used one of the two mounting screws. So, I redesigned this part. It works well enough, but I get clunking sounds from the centrifugal fan due to the printer arm motion being the same as the fan bearing, so the fan floats up and down on the spindle.
The 50mm blower fan is held in position by screw tension only. It has a slot for a captive nut that I had to clean out and open up a bit with my Dremel.