Fascinating to say the least Leafcutter John is making contact microphones and he grows the crystals using products from the supermarket, then cases them and uses high quality cable and connectors. On his sound cloud page you can listen to the samples he has made with the piezoelectricity home brew. I was very taken by the sound created using this method and will be trying to make one myself. This is great way to make sample packs for Ableton Live, original and with a quality I have never heard before.