Amazing resonance experiment!
So this experiment is the Chladni plate experiment. I used a tone generator, a wave driver (speaker) and a metal plate attached to the speaker. First add sand to the plate then begin playing a tone. Certain frequencies vibrate the metal plate in such a way that it creates areas where there is no vibration. The sand “falls” into those areas, creating beautiful geometric patterns. As the frequency increases in pitch the patterns become more complex.