I was tired of my earbuds getting destroyed in my pocket so I created a small box I could carry in my pocket to hold them securely. Over time I ended up adding a few other things in the box like some allergy meds and a microSD card.

The model is thoroughly parameterized so you can adjust the size to suit your needs in Fusion 360.

The box is pretty sturdy and won't open without some intentional force using the finger grips on the ends.