A simple geometric heart shaped box. Composed of a square and two half circles.
Use it as a jewelery box, to put a ring in or just as a toy.
The lid is flush on the inside and outside with a hidden stepped groove to keep it on.
The size is easily customised in the openscad file: all you need to specify are width, height and wall thickness.
Width is the distance from one of the flat sides to the tip of the opposite round side (eg. the width of the square that the heart would just fit inside).