Afraid to wander from your room to the kitchen or bathroom in the dark of night? Fear no more! By turning a common water gun into a light gun you can be protected from the creepers that lurk in the darkness!
You will first need;

-Water gun
-6 Volt battery
-8ohms resistor
-Clear plastic cap to enclose LED and fit as the button
-red LED
-3.5V light bulb and the screwy part with the legs.
-5 medium pieces of wire
-ribbon
-Electrical tape
-Double sided tape
-Two squares of foam(small enough to fit on a penny.)
-two pennies

Start by taking appart the water gun and removing it’s insides.

 This can be accomplished with a sharp blade or a tool that both heats and cuts through the plastic. Avoid saws since they will most instantly break the toy gun.

 Now that you’ve gotten through the most difficult and potentially dangerous part of the project you can make a choice of buttons. The toy gun already has a push button mechanism that works with a spring. This can be maneuvered and used once the small hose and rest of the plastic parts are removed. In my case I chose a light up button using an LED and a plastic cap that once belonged to a pencil eyeliner.

I had to cut the cap to fit into my toy gun, that may not be necessary for everyone since not all water toy guns are the same.
Shown here is the LED inside the plastic cap.

In order to create a switch I attached two pennies, each to a piece of foam using double sided tape. The  foam only works as a way to keep the pennies in place and does not need to be conductive. The pennies themselves will get soldered into the circuit.

 Speaking of which…

 Here is what my circuit ended up looking like after I soldered all my pieces in place. In order to keep my LED from burning out while I soldered it to my resistor i used a hair clip (not shown). 

To make this circuit work and so that both LEDs would light up at the same time I attached a wire going from the positive end of the battery to one of the pennies. The negative end of the battery was attached to one of the legs of the big white LED and another also attached to the same leg of that LED ran to the smaller red LED’s cathode leg. On the red LED’s other leg was the resistor,soldered. Attached to the resistor is a wire that connects to the second penny and another wire that runs to the main LED’s other leg.

Making the circuit fit and keeping the wires from shorting is the trick. Use electrical tape to cover up naked wire.

Double sided tape comes in handy once more to keep components like the foam in place and to attach the button to the other foam. Like so ->

Before Sealing the cover put a small ribbon between the two pennies so that they do not touch until you plan on using the gun, it’s a one time use ‘safety’. This also allows you to preview the the whole itself before sealing the gun up again with hot glue.
Pull out the long end of the ribbon from the hole that is usually used to fill the water gun up with water and make sure not to pull the whole thing out.

Once this is done and you are confident with the integrity of your circuit you can seal up the water gun with silicon using a hot glue gun.

 The Ribbon may cause trouble and get accidentally pulled out if left hanging willynilly so I would recommend carefully tying it into a bow. This keeps it short and compact but also easy to pull out when you are ready to do so.

 It’s also pretty cute.