A metal plate driven into vibration by means of a violin bow. First explored by Ernst Chladni (pronounced "Klahd-nee"). Sprinkling salt on the plate reveals nodal lines, specific to the various normal modes of the plate. In 2015 we had fun with it at the Science Slam. Kids can master the technique pretty quickly. Maarten can loan you the plate. We'd need to track down a violin bow.
Not for those on a low sodium diet!
This artist takes the visuals to another level!