Foucault's Pendulum 15"
When Leon Foucault set up a simple experiment in 1851, little did he know the importance of what he was about to tell the world? While it was path-breaking, brave, and a novelty at that age, it's different now - You don't have to convince anybody anymore that the earth rotates around the sun.
As Foucault's Pendulum twirls through the fine sand, it gently creates an ever-changing geometric pattern. The patterns get bigger, then more minor, and then more extensive as the pendulum's arc changes.
Material: Plastic, metal, and fine sand.