I am using an Arduino (Atmel168 development board) as the time-lapse controller, but you can use any micro controller.
This was originally made for Day 5 of Thing A Day.
Step 1: Go get stuff.
1 - digital camera
1 - small 2-pin socket
1 - 5V relay
1 - Arduino (or other micro controller)
Step 3: Press my buttons
Step 4: Socket to me.
Make sure when placing your socket that you have enough room for both the case to close and to rip a hole in the side of the case to poke the socket through.
Step 5: I'm sticking with you
Step 6: Close the case.
Step 8: Plug and play
Plug the relay coil pins to Pin 7 of the Arduino and ground on the Arduino. The relay coil pins are the two pins that aren't towards the ends of the tube.
The two pins towards the end of the long tube go into the socket pins in the camera. It does not matter which wire goes in which socket pin.