The Best Way to Make a Homemade Air Gun

The Body

Cut a spray bottle in half to make the handle. Use a craft blade to cut the bottle first, then trim off any jagged edges with scissors. How far down the spray bottle you cut is up to you; it needs to be far enough down so that it is comfortable to hold. About 3 to 4 inches (7.6 to 10.2 cm) below the cap would be ideal. Discard the bottom part of the spray bottle. If your spray bottle has a molded handle, cut just below the molded handle. If you can't find a spray bottle, use a small air pump instead, like the kind used to fill basketballs. Be sure to take the unscrew the top nozzle. Wrap some colored tape around the bottom, cut edge of the spray bottle. This will add a little design, and hide any jagged edges.

Trim the tube inside the spray bottle until it is level with the cut edge. After cutting your spray bottle, you will likely have a plastic tube sticking out from under the cut edge. This will only get in the way, so trim the tube with scissors until it is the same length as your cut bottle. You don't want anything sticking out from under the cut edge. You can cut the tube a little bit shorter, if you want to. This will prevent it from getting caught on anything.

Drill a small hole in the bottom of a plastic water bottle. The hole should be big enough for the nozzle of the spray bottle to fit though. You can drill the hole with an electric drill, a dermal, or even a pair of scissors. Make sure that your bottle has a sports cap. They are the kind that you pull to open, and push to close. Don't use a standard water bottle with a flat, twist-on bottle cap.

Open the the spray bottle's nozzle, then glue it into the hole. Twist the nozzle on the spray bottle until it is in the "open" position. Draw a ring of hot glue around the nozzle, then push the nozzle into the hole. Wait for the glue to set, then add more glue around the seam. Adding more glue around the seam is a must. You want it to be airtight. If it is not airtight, there won't be enough pressure, and the air gun won't work.

Glue a straw on top of the sports bottle cap. Pull the cap open first, then place a straw right over the opening. Draw a line of hot glue around the seam. Be careful not to get any glue inside the straw, or you may block the hole. You need to be able to push and pull the cap close/open. If you want something sturdier, you can use a short plastic or metal tube instead. You can also take a ballpoint pen apart, then use the body.

The Trigger (Optional)

Wrap the end of sturdy, metal wire around the bottom of a circle hook. Cut a length of wire that's long enough to reach from the water bottle's cap to the spray bottle's trigger, plus 2 to 3 inches (5.1 to 7.6 cm). Wrap the end of the wire around the bottom of a circle hook to secure it. The circle hook needs to be big enough to fit over your water bottle's sports cap. Don't use all off the extra wire when securing it to the hook. You still want another 1 to 2 inches (2.5 to 5.1 cm) for later.

Push the circle hook over the sports cap top. Hold the small bottle firmly in 1 hand as you do this so that you don't accidentally break the gun apart. If you can't fit it, position it so that it sits comfortably on top of the cap, then secure it with lots of hot glue. Make sure that the end of the ring and the wire are pointing down.

Break an L-hook near 1 of the screw holes to create a ditch. You can do this by snapping it over the edge of a table or with pliers. If you can't find an L-hook, or can't break one, use a popsicle stick instead. Cut the popsicle stick in half, then use a folded piece of sandpaper to carve a U-shaped notch into 1 end. You want the screw hole to be exposed. The resulting ditch or groove will act as a groove for the hook/lever.

Glue the broken L-hook under the water bottle, close to the cap. The circle hook should rest comfortably in the groove created by the screw hole. If you'd like some extra security, you can tie the L-hook to the water bottle using zip ties.

Fold the end of the metal wire into a loop. Make sure that you can comfortably reach the loop with your forefinger. If the wire is too long, you may need to cut it. Twist the end of the wire around itself. This closes the loop and keeps it from coming undone. The loop will make the trigger. Make it big enough for your finger to slide through. Wrap it around your finger or a highlighter to ensure a good fit.

Using Your Air Gun

Cut some Q-tips in half. If you are using the kind that are hollow inside, you can glue some toothpicks inside to make them more lethal. Only do this if you plan on being responsible; never shoot your toothpick bullets at another person or animal. You can also use other missiles, such as lollipop sticks or toothpicks.

Push a Q-tip, fuzzy-side down, into the straw. If the Q-tip won't slide into the straw easily, you'll either have to pull the cotton batting off, or cut it off with a pair of scissors. You can only load 1 Q-tip bullet at a time.

Push the sports cap shut and pump the gun. Simply squeeze the spray bottle trigger repeatedly. As the small bottle fills with air, the trigger will become harder and harder to pull. Once you can't squeeze the trigger anymore, stop. As you pump the air gun, the pressure will build up, making the trigger harder to pull. Once enough pressure builds up, you won't be able to pull the trigger anymore.

Aim your gun, and fire. If you made a trigger for it, pull on the metal loop. This will open the sports cap and send your "bullet" flying. If you didn't make a trigger, simply pop the sports cap open. The built-up air will push the bullet out, and send it flying! Remember to be responsible. Never aim sharp missiles are other people or animals. Never aim any missile at a person's face, even if it is soft, like a Q-tip.