So I was looking for a generic powerbank holder for the Quest 2, I didn't quite found something that would fit my needs without drastically changing the headset band, so I just made a redesign of an existing model that should fit more powerbanks while being easier to print.
You will need some kind of strap to hold the battery in place. Print at 0.2 and you should be fine.
The author remixed this model.
I made it easier to print as it is now flat, the space is larger so it can hold bigger powerbanks with a ledge so they don't fall, less material is used in order to print it.