MakerHawk 4pcs Analog Ceramic Piezo Vibration Sensor Module 3.3V/5V for Arduino DIY Kit: Amazon.com: Industrial & Scientific
Amazon.com: MCFT-9T-18A1-115 - Piezo Element, Diaphragm, 18 kHz, 1 kohm, 3000 pF, 9 mm, 0.22 mm (MCFT-9T-18A1-115) (Pack of 50) : Industrial & Scientific
Amazon.com: Piezo Electric Crystal Earphone Sensitive High Impedance Ceramic Ear Piece 3.5mm for Transistor Radio/Crystal Radios DIY Electronics Projects 1/8 inch Audio Jack Connector Wire Piezoelectric Element : Electronics