My first attempt at iPhone 15 case.  My daughter got a new phone, and the case (ordered online) was not due to arrive for a couple of days.  I had a reel of flexible PLA, and figured that I could print one.  But I couldn't find any existing models online, so I had to roll my own.

This is a revised version, with major parameters in a (FreeCAD) spreadsheet.  You can tweak to adjust fit tolerance, wall thickness, etc.

The default settings are about right for Flashforge Flexible PLA: you might need to adjust them to get good results with other filaments.   BTW, it should be obvious: regular PLA is too rigid and not stretchy enough to make a useful case with this model.  (You wouldn't be able to squeeze the phone through the opening.)