Quantity   Component name
1 × Plastic enclusure. Should be comfortable to hold with a flat top surface Mine is 102 x 61 x 26 mm
1 × Teensy 2.0 AVR prototyping board
5 × Push button Not too big.
1 × A piece of perfboard
1 × Copper tape I'll try to make a touch wheel with this
1 × Cable lead-through Protects the cable on its way out of the enclosure
1 × A piece of cable (3 wires or more)
1 × PCF8574A I²C I/O expander, reads the buttons
1 × 100 nF capacitor for PCF8574A
2 × 4k7 resistor I²C pullups