Here is my design for a Dental Night Guard Case. It consists of two parts that you can print together or separately, if you wish a two-color appearance. To connect the two halves, simply insert 1.75mm Filament into the Hinge mechanism. You might need to clean up the hole a bit to make it fit. Works perfectly for me.
I used 0.2mm layer height and pretty basic PLA print settings. Around the hinge I used the functionality of PrusaSlic3r to reduce layer height to 0.05 to make them smoother.
The author hasn't provided the model origin yet.