If you want to print PLA fast airflow is king, a standard 40 mm fan just doesn't move enough air for that, so i created an attachment which accepts a standard 50 mm blower fan.
To get it perfectly dialed in its height adjustable. ( Optimal position is 0.5mm away from the bed surface when the nozzle is at 0 )
Hint: If your in the market for a new 50mm blower buy sunon branded ones, they are great.
Added a 90° tilted Version as i had vibration problems with the fan in a horizontal position
Print upright with supports so the layers dont split for the 50mm fan Press fit.