Drum triggers and commercial contact mikes are often made from piezo disks and sold at absurdly high prices. As gratuitous markups are anathema to the hacker, making own cheap contact mikes is a satisfying way to while away an evening. Contact mikes are great for greatly amplifying sounds hiding in everyday objects. The trick is making firm physical contact with the vibrating object. The influence of John Cage (1912–1992) on American avant-garde music cannot be overstated. In the aftermath of Cage’s Cartridge Music, many sound artists sought affordable techniques for amplifying mechanical vibration and microscopic sounds. Since the mid-1970s, the proliferation of piezo disks in beeping appliances has put contact mikes within reach of anyone with a soldering iron. Recently, several radical turntablists have taken the cue from Cage and extended their technique beyond the vinyl groove. Many artists have used piezo contact mikes to record inaudible or elusive soundscapes.