Be careful with this step; putting too much water will over-dampen the piezo element and result in nothing, and under-filling it can damage the piezo element. Place the piezo element in the pan and fill with distilled water until it is just barely coming up to the sides of the piezo element. The water actually gets drawn up from below the element, so do not submerge it! The water level may require some adjusting to get right.

Congratulations, you've just assembled an ultrasonic vaporizer! This exact mechanism is used in humidifiers and essential oil misters due to its reliability and low cost of manufacturing. This can also vaporize isopropyl alcohol if you want to smooth out the surface finish of 3D printed objects!