This sorting box is designed so that an infinite number of duplicate boxes can be stacked on top of each other. The carved-out slots are so you can insert small things even when the box are stacked on top of each other. Other than stacking (as seen in the picture) you can flip the box over and use it as a decorative stand.
Side note: The boxes do not have a super tight fit but will stay together quite well. The looser fit is so you don't have to struggle to stack them, as long as you line it up pretty well it should easily slide together.
Enjoy!
My print settings:
The author hasn't provided the model origin yet.