A derivative of agwn's sleeve, but with an extra box on the side that's a press fit for a small slider switch.There is a small quadrant shaped hole through which you poke the positive lead from a battery clip. Cut the red wire and solder it across the switch and pass the black wire through the round hole. Twist the wires together.The switch is a common or garden variety I had lying around, but it's a nice snug fit and needs no glue.