Step 1: The Makey Makey
The Makey Makey works by detecting a circuit that is completed through you and whatever you've connected the Makey Makey to. The device is based on an Arduino micro-controller. it comes preloaded with code so that it emulates a computer keyboard. Each contact point on the Makey Makey is mapped to a button on a standard keyboard. If you click on an arrow it triggers a corresponding arrow press on your keyboard. Each contact has hookup points so you can attach alligator clips. The ground wire must be clipped to you or you must make contact with it when you press a button.
Step 2: Draw Your Keypad
The Bare Conductive paint comes in a plastic tube that makes it easy to squeeze out and draw your keypad. For this project I painted the keypad onto a piece of paper. It can help to layout the keypad first by drawing it in pencil first. Paint it thick to help the conductivity. It helps to bring the conductive traces up to the edge of the paper so you can easily attach the alligator clips to the traces. Finally wait for the paint to thoroughly dry, it's less conductive when wet.
Step 3: Connect and Play
When everything is dry it's time to hook it all up. Connect the alligator clips to the Makey Makey and then finally to your drawing. Find a game to play online, the Makey Makey site offer some good recommendations to get started in their how-to: http://www.makeymakey.com/howto.php. Finally hook the ground wire to you. I clipped mine to my fingernail so it would com in contact with my finger. Now enjoy gaming with your very own custom keypad.