Creality Sermoon D1 8025 stepper driver fan mount

Designed for a Nidec UltraFlo 8025 fan since it has only 0.05A consumption. But should fit any 8025 fans - if the bolt holes don't line up perfectly you can just use double sided adhesive tape on the inside of the mount, it's more than enough. 
That being said, I wouldn't exceed the current rating of the original fan (0.07A) significantly just to be on the safe side (at least as long as you drive it from the original 2-pin outlet)

The mount and the fan protrudes 10mm into the chassis (just like the original one) and I've attached taller, 28mm legs to ensure enough clearance for air intake. You might have to slightly rearrange some cabling inside if it's in the way.

I also printed an airflow guide for the PSU fan which directs hot air towards the back and ensures none of it is recirculated by the stepper fan (that 3D model is not included, I might upload it separately)

Result: 

Obviously at least 10x better airflow, and the bonus: after the high pitched noise of the original, this fan's low/mid frequency noise feels downright soothing. The slightly uneven blade placement of this model (U80T24MHA7-52) also helps a lot to achieve this.

Instructions / tools : 

an oscillating multitool and a drill to get the blade started at the corners.

Eye, ear and respiratory protection highly recommended. 

Be precise as you can so there is no air leakage at the sides.

You will also need taller, at least 28mm legs to ensure proper clearance for air intake.
 

Print instructions: 

PLA is fine, the side eyelets will need support. Use a 0.6 nozzle and chunky setting for a quick print.

Disclaimer: 

it is not a perfect design but didn't want to be OCD about it. As you will see the sides of the mount slightly protrude in the middle, it should have been rounded and narrowed but I didn't notice any additional noise or meaningful airflow restriction due to this at all.

Disclaimer 2: 

while this fan vastly improves cooling, there's still the outstanding issue that the stepper driver fan only activates when the parts cooling fans are also active. This presents possible overheating issues during ABS etc prints but there's plenty of info in the FB group on how to fix it.

Recommendation: 

you can easily add a DC motor speed controller [for brushless motors] since it still should deliver at least 5x more airflow even at half speed and even lower noise. Although at this point the PSU fan is by far louder than this one.