Here is a Chladni Plate that connects to your smartphone and lets you experiment with sound frequencies to generate cool Cymatic patterns. The SoundScribe from Cymatics Lab connects to your phone or tablet wirelessly but also has a 3.5 auxiliary input. It has a solid pine construction with a 12″ carbon fiber plate.
You can use this Chladni plate with various tone generators for iOS and Android. It measures 13-3/8 x 13-3/8 x 1.5″. You can find out more about it here.