Frog boxes

This is an interactive installation about a family of curious boxes. The audience interact by closing boxes, the boxes respond by randomly popping open as if curious to know what happened. The boxes are made of 3mm ply. We spent quite a lot of time thinking what could be the simplest opening mechanism. Finally, we settled on a delicately balanced magnetic latch. When not activated, a small magnet in the lid keeps the lid closed against a spring at the back of the box. A solenoid mounted in the base, right across the magnet is activated momentarily with a magnetic field of reverse polarity to open the box. The slight force of repulsion between the magnet and the solenoid is enough to help the spring to pop open the box!