Print right-side up without support FOR THE NON ROUNDED EDGES VERSION. Print right-side up with supports for the ROUNDED EDGES VERSION. 15% infill is fine, and a cool thing you could do to make it very secure would be to add magnets to help it not move around and stay more inside but it is very hard to do that right. There is ALSO a version with rounded edges, so if you want that you can pick that file instead but the edges being rounded is the only difference.
The author remixed this model.
Cover which the original did not include.