How to make your own Contact Mic (no solder) - YouTube
DIY Contact Mic Tutorial – Deferlow
Piezo contact microphone hi-Z amplifier – low noise version – Richard Mudhar
Building (or Buying) Contact Mics – Zach Poff
Contact Mics Contact Microphones Piezoelectronic Transducers Piezo Microphones Weirdo Gadgets Designed by Crank Sturgeon Manufactured by Huso Solutions since 2007