I created a slot to hide credit cards inside the cover of the iPhone 13 Pro Max, to always have at hand a card or document in the same standard format 86x54mm.

I prefer to print the cover with the back upward to have a custom finish in the top (I like Hilbert Curve) and keep a larger thickness around the camera lenses. This involves a substantial use of internal support: to remove it I recommend you start from the opening of the cameras and separate on the front the support from the cover with a small precision knife.

The result in my opinion is excellent: it is a very durable and minimal cover. Let me know what you think!