But light is intangible -- it would not be able to trip the more traditional Rube Goldberg mechanisms. Therefore, the team chose mechanisms that required heat -- focus a beam of light tightly ...

All featured a 220V AC supply, a sensor (either an IR distance sensor or a light barrier) to detect the ball, and an Arduino. Actuators were built from hair dryers and portable fans.

Max Planck Institute of Quantum Optics. "A 'pin ball machine' for atoms and photons." ScienceDaily. ScienceDaily, 16 April 2015. <www.sciencedaily.com / releases / 2015 / 04 / 150416093924.htm>.