Print at 0.2mm layer height with no supports.  Default PETG Prusa profile works great.

This is an improvement of my original design:

1. Improved grippers for comfort (fingers rest closer together)
2. Beefed up hinge
3. Tightened tolerances for a better seal

I also added a optional version with wider gaps if anyone has problems with the hinge sticking.  Default is 0.2mm gap.  The loose version has been increased to 0.3.