Have you seem the famous pendulum balls that never stop swinging?
Get a sculpture that has the same concept where it just never stops moving. It consists of moving sticks unlike the ball pendulum and once you get it moving it just won't stop moving. This is done through conserved kinetic energy as the sticks swing from one side to the other. Since the pendulum doesn't lose kinetic energy due to heat, almost all of the kinetic energy stays in the pendulum which keeps the sculpture in motion.
This would be a great sculpture to have in offices, conference rooms, or waiting rooms.