I wanted a box that would snap together and where every side would be a separate easy-to-print piece (no support structure). Since all the pieces (except for the handle) are printed in a horizontal orientation, this will allow me to have intricate designs on the sides and top without worrying about support structure. This box is held together by the latches on the top and bottom and not by friction. This particular box is a cube that is 100mm on a side.
I had problems with PETG with the hollow infills creating vertical strands that would make bubbles in the final product. Since the sides, top and bottom are only 2 mm thick, I just used a solid infill. For the posts and the handle, I used a star pattern with 50% infill.
The top has a clearance hole for a #8-32 screw and the handle has a pilot hole to drill for a #8-32 tap and then the tap is used to create the threads. Of course, other similar sized screws could be used.
The top and bottom are essentially the same piece except the top has a hole for attaching a handle and only two latches. I originally had four, but it made it too difficult to take the top off.
For the pictures, I used contrasting colors to make the individual parts stand out. This is not intended to be a style recommendation! The final picture shows a box printed with all the same color in PETG. The multicolored box is all PETG with PLA sides. Other plastics should work fine with the only doubt being how the latches on the top and bottom would perform since PLA is more brittle than PETG.
The function of the brace inside is to hold the box together when the top is removed, as otherwise the structure tends to collapse. The sides are a 2mm plate with lips on the top and bottom to engage with the latches.