This can be printed with a 0.4mm nozzle without supports however I recommend printing with a 0.2mm nozzle, 0.06 layer height, and tree supports. I have used PLA only so far because it is flexible enough to snap on and does not pop off easily.
The author remixed this model.
I took the back off this case, scaled it down a bit, and added a planar rim to the top to act as a guard and allow it to be printed on it's face.