small plastic container (pop bottle, small spice container, etc.)
breadboard+leds and battery (adjust voltage accordingly)
Step 1: Making the switch
if you cant get your wires in through the mouth of the container then make two small slits (keep the slits seperated by making one, then making the other on the opposite side), run the stripped wires through the slits and secure them using electrical tape, after that cover the slit with hot glue or epoxy to ensure nothing will leak.
i cant stress this enough but ensure there are no leaks! now put this aside and lets look at the simple schematic i made.