Richard from the Netherlands built this split-flap game as a gift to his niece. Actually, the gift is inside, but you have to win the game to get it!
The wooden box and all the components for the Split-flap display were made on my CNC machine. I used 2mm thick plastic to mill out the 36 cards in the display. The wheels holding the cards and the pulleys for the cardwheel and stepper motor were milled from left over thick plastic blocks. I milled a 10 teeth pulley (XL037) for the stepper motor and a 40 teeth pulley for the cardwheel, giving me a ration of 4:1 and with my 1.8 degree per step motor, this gives me plenty of accuracy to make sure I display the right cards. I did build into my arduino code I can easily change the offset for each card to fine calibrate. I had to do this, as not all my cards where equal in size.