I have designed my own toothbrush case with a snap in closing mechanism.

Most of the models which I found online have a very fragile closing mechanism.

There are files for multicolor printing, and also for single color, with a cutout model.

Printing instructions:

layer height: 0.2 mm

supports: only for body

infill: 15%

wall loops: 2

Assembly instructions:

Just snap in the cap into the body.