Electronic flute based on STM32F100

Built this little toy from scrap parts this evening. No PCB, all components glued to piece of FR4 with epoxy with their pins up in the air, then soldered together with thin wire and covered with epoxy again. Sound is emitted by Murata pklcs1212e4001 and pklcs1212e2000 (in parallel to compensate frequency responce) - amazing piezo-buzzers, drawing less then 0.3 mA.