A kraakdoos or cracklebox is a custom-made instrument, in the form of a noise-making electronic device. It is a small box with six metal contacts on top, which generate various unusual sounds and tones when pressed by the performer's fingers. The human body becomes a part of the circuit and determines the range of sounds possible, thus different people shall generate different results.
The concept was first conceived by Michel Waisvisz and Geert Hamelberg in the 1960s, and developed further in the 1970s when Waisvisz joined the STEIM foundation in Amsterdam, Netherlands. The kraakdoos is a simple device, based on a single operational amplifier (one of the earliest models to be produced) and a few transistors, and can be constructed with only a basic understanding of electronics.