1x NEMA 17 Stepper Motor. Lower internal impedance is preferred, especially below 5 Ohms. Do not expect good results with impedances greater than 20 Ohms.
4x Diodes, low-voltage drop, higher current than 1N4148.
4x Capacitors, 1000uF or higher. Voltage > 25 VDC suggested. 3300uF works well.
1x Number 6 Board or other Atmega32 dev board (7805 regulator, Atmega32, 16MHz crystal, 2x16pF capacitors)
(optional controls) 10 Electrical Momentary Contact switches (preferably that feel good on the fingers)
(optional controls) 8 potentiometers. Value from 10K to 1M. 50K-100K are recommended.
TIP120 or similar NPN Power transistor
Potentiometer between 5K and 100K. 10K or 20K is recommended.
1 Low-Ohm speaker. 4"-6" inches in diameter or larger if possible. Volume/Efficiency are greater with heavier or more powerful magnets.
(option) A beloved speaker from a dead stereo, decorated with decoupage or at least a color printout.
(option) 1 Heavy Cardboard Tube, the same diameter as your speaker. Brackets or other mouting for the speaker.