Cartier has launched an interactive gift display that lets passersby control the fancy boxes in their window on 5th Avenue in New York City.

The project, called Reach, features various red boxes displaying shiny jewelry which people can open and close by moving their hands, giving them reign over what is usually off limits.

It’s a deceptively simple setup, but behind the scenes there’s a complex network of equipment featuring a Mac mini, a projector, a high-precision sensor, and mechanized boxes fitted with motors controlled by microcontroller boards.