There isn't really anything available for this phone so I prepared a simple case.

Can be printed in hard or flexible material.

Optional: Hole in the back to be able to attach a pop out finger holder (need to disassemble them to squeeze the rubber through the hole).

Optional: Thin version that makes the buttons more easily pushed (I prefer the depth of the original),.

Optional: Version that covers the essential button entirely (untested).

Note that the version in the photos has been slightly updated to better align the holes on the back.