There's 2-3mm of clearance between the bottom of the fan and any connectors underneath, so you can plug stuff into the CNC fan port. I used a random 30mm x 30mm fan I had laying around.
I cut off a couple arms of mine because I have a input-shaper board blocking the way of them but if you don't have that everything fits fine.
It brought my temps down about 6 degrees C.
The author remixed this model.
I remixed it to use a 30mm fan instead of a 40mm fan so I could use a small raspberry pi fan I had laying around.