This case takes a 4010 fan no screws are required.
For PWM this has screwless slots (2x) for the PWM module which you can get here at Amazon.
Fan I used is Orion 4010 5v 2-pin fan. I am running it via a 3.3V pin on Pi for lower noise.
The TOP and BOTTOM of the case are snap-fit.
Rpi needs to be screwed on the bottom portion and takes the M2 screw.
Snap-Fit inspired by Malolo design
The author hasn't provided the model origin yet.