My architect friends Lorenzo Bini and Roberta Pezzulla made this little project for a very young and dynamic client: Lorenzo’s 6-month-old goddaughter. They wanted to make a box that the child could use her whole life to store small, personal, precious things. So they created the UnaBox, taking inspiration from an Indian box (by an anonymous designer) that had an obscure opening system with 2 pivoting lids.

The box’s dimensions are based on the golden ratio, and it allows access only to patient and curious people; many adults have tried to open it and failed. Here’s how to build one yourself!