A simple heart shaped box that can hold a small gift like jewelry. 

I would suggest printing the outside in something stiff like PLA or PETG, while printing the inserts in TPU. Everything should be set up in the 3mf file. The top and bottom pieces snap together at the hinges with the balls clicking into their spots.

For full honesty I do not have any red or red adjacent filament, so I printed this in green and edited it into red.