The purpose of the Makey Makey is to take everyday objects and add a computer interface. Using the materials in the kits you can do tons of different things from making a banana into a piano or creating a giant game controller from paper and Play-doh. The kit contains a circuit board, alligator clips, and a USB cable, the kit uses closed-loop electrical signals to send the computer either a keyboard stroke or mouse click signal.
Here is the drawing piano set up.
This is how the circuit board looked.
Here's a video of me playing a drawing like a piano.