For the course Making Things Interactive I am taking this fall, I had an assignment to make a switch. I decided to make a footswitch, which you can see in action here:
To make the footswitch, I used two cutting boards that were laying around the house. To the bottom board, I taped a sheet of aluminum foil and made a border of foam tape around the edges. On top, I stuck the second cutting board with a wire taped to the underside. The foam tape created separation between the two boards, yet was springy enough that when a person steps on the top board, the wire taped to its underside comes into contact with the aluminum foil on the bottom board, closing the switch. When pressure is removed, the top board springs up again, opening the switch.