NEMA 17 stepper motor cooler for 40mm fan (even for helloBEEprusa)

I build the cooler cap with Sketchup for my helloBEEprusa, because the stepper motors got alarming hot when I printed on higher speeds. But it will fit on any NEMA 17 Stepper as this is a standard size. The thing is optimized for easy airflow and has a build in safety limit so that it is impossible to push the cap too near to the back of the stepper.
The design regards the FFF process and the tolerance is made for a tight fit so that no glue or screw is needed.
I tried to reduce the amount of