For my wedding I wanted a simple photobooth. It prints pictures directly, and saves them on the Raspberry Pi.
The camera/printer are USB-devices. There is one big button, and two leds. One led is inside the button and will blink when the camera is not in use. The second led is in mounted on the front of the camera-box, and indicates when a picture is being taken (the smile-led)
This is how the camera-box inside: