The most important part is the Single Li-ion Battery Charge and Discharge Integrated Module Type-C Input 5V 2A. The rest is up to you.
You can choose any size or capacity 3.7v Li-po battery that suits your needs. The button can be different too. Assembly is very simple, just use some hot glue and M3 bolts for fan mounting."
Schematics:
The author remixed this model.
Here's a summary of the key differences between the two models:
Size: