The classic Chladni figures, drawn as the nodal set of two degenerate modes cancelling each other. Frequencies are for a steel plate 30 cm square and 1 mm thick. Click any figure to hear it and watch the sand find it.
A circular membrane fixed at its rim. The first number counts the nodal diameters, the second the nodal circles. Frequencies are for a head 30 cm across at the tension of a tom.