Instructables user XenonJohn writes:

This is an Arduino based iPod hackaudio project that allows you to select tracks for playback from an attached iPod Touch simply by placing cards on flat upper surface of the machine.

The cards can be placed in small plastic boxes with a picture of the album cover on one side to make small blocks more suitable for small hands to manipulate. Originally designed for disabled child. Since then people, teachers I know and so on, have been urging me to “do something with it” so this is an easier to set up and use quasi “tablet” version.

Membrane Matrix Keypad + extras – 3×4— Punch in your secret key into this numeric matrix keypad. This keypad has 12 buttons, arranged in a telephone-line 3×4 grid. It’s made of a thin, flexible membrane material with an adhesive backing (just remove the paper) so you can attach it to nearly anything. The keys are connected into a matrix, so you only need 7 microcontroller pins (3-columns and 4-rows) to scan through the pad.

We include a 7-pin extra-long header strip so you can plug this into a breadboard with ease.