My son (10 years old) designed this box as a present for one of his teachers at school. It’s a “barrel box” with a little floating shelf inside, which raises and lowers when you open and close the lid.
The whole thing was designed in Fusion 360, which included modeling all of the different parts, hinges, joints, etc. to ensure the movement would be right.
The slats on the side of the box ended up being somewhat flimsy on their own, so inside the box are several ribs mounted to the slats for strength.
Underneath the internal shelf are four little 3D printed pieces which hold the screws to the underside of the shelf.