A simple project turning out-of-service smoke detectors into something new such as guitar pedals or pickups, sensor gadgets or other simple devices.
Me and my best friend Hallmar Gauti worked on making a simple piezo-based pickup and pre-amplifier for acoustic guitars and other string instruments. One of the main reasons for this is that piezos are one of the main components in smoke detectors (they make the noise and have to be very reliable and standardized).
Use the ionization chamber for a µcontroller-based smoke sensor for applications.
Perfect use for parts in a DIY project.