It uses an Sainsmart Arduino mega and Doomsday Clock shield (wiki here http://www.samuraicircuits.com/MediaWiki/index.php?title=Doomsday_Clock_Shield.) Use the iDoom header files, not the DoomsDay header files.
I have 6 momentary buttons wired to 6 digital pins on the Arduino. I used a breadboard for the connections for the buttons and resistors to the Arduino. The box is the box from Radio Shack that contained the SideKick Basic Kit For Arduino. Everything fits perfect in it.
The system is broke down into 3 sections, 1 for each daughter. Each section contains 2 buttons, and 2 7-segment LCDs. When turned out each section starts at 50, so they can go up or down.
When the black button is pushed, it plays the first few notes of the Mario theme song, and then adds 1 to the number. When the red button is pushed, a low single note is played and 1 is subtracted.
I'll get pictures of the boards and do up a wiring diagram as well.
Here are the pins I use for the buttons:
Pin 22-Child 1 count up
Pin 23-Child 1 count down
Pin 24-Child 2 count up
Pin 25-Child 2 count down
Pin 26-Child 3 count up
Pin 27-Child 3 count down