For this project, you will need the following:
The Raspberry Pi B+
A small section of a prototyping board
USB power supply and a micro USB cable
High current 5 V power supply
Several 1000 uF capacitors (www.maplin.co.uk/p/1000f-35v-85c-radial-electrolytic-capacitor-vh51f)
A breadboard (www.maplin.co.uk/p/ad-100-breadboard-ag08j)
A strip of 0.1-inch pin headers
0.1-inch male-to-female pin jumpers
M3 nuts and machine screws
Cable ties
15x empty glass bottles
15x micro servos
A 15x servo mount base
A 15x servo mount
I found that the larger 500 ml bottles are better for this as opposed to the 330 ml ones. Anything larger then 500 ml will still work; however, they may not fit on the servo mount base correctly (this should not stop the servo from working correctly).
To make tuning easier, it is recommended that you use the same size bottles for all the 15 notes.
The amount of capacitors you will need is determined by the power output of the power supply you are using and the number of servos...