We built a prototype for a large musical keyboard which can be mounted on steps or corridors. We experimented with various sensors - piezo, Velostat, ultrasonic, laser+LDR etc. For the first scale prototype, we used piezo elements sandwiched between two laser cut 3mm plywood sheets. In between the two plywood sheets, we added a layer of white foam for springiness and to help protect the piezo elements. We built one octave using 8 piezo elements connected to an arduino nano. On the output, we connected an ordinary buzzer. 

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