This is a fun little project i made for a school contest that is indeed very cool. It only costs twenty dollars (if you have the tools). It takes around about 1 hour to make. It is a very cool way to pass the time. PRECAUTIONS: This gun is intended for +10 or older and should be shot in the appropriate place. If you do get shot, IT WILL HURT, so i recommend you don't do it! I will take you through the steps on how to make it. I hope it is easy to follow and pays off.

Step 1: Gathering Materials

Materials:Two screws (small)
1 1/2 inch pvc pipe cut to one foot (which is the barrel)
2 inch pvc pipe cut to eight inches (which is the chamber)
one coupling reducer from 2 inches to 1 1/2
one female coupling 2 inches
male coupling 2 inches
pvc primer and pvc cement
and a grill lighter.

Tools:
Drill
chop saw
tape measure
hairspray
and a pencil.

Step 2: Cutting to the Right Length

Now this part requires:

Chop saw

hands

You will need to take both of your tubes and cut them with the chop saw to the appropriate lengths. Take the 1 1/2 inch barrel and cut it into one foot long. Cut the 2 inch tube into 8 inches long.

Step 3: Dryfiting

The next step is simple. Dryfit the tubes and make sure they fit.

Step 4: Gluing

Now, take the primer and the cement. Add the primer to one end of the 1 1/2 inch and put primer on it and add the cement, but also prime and cement the 1 1/2 side of the reducer and put the 1 1/2 inch barrel in the reducer.Then, take the 2 inch and add primer and cement to both ends of it. Then, quickly add primer and cement in the female coupling and as well as on the reducer. Let that dry from 2-3 minutes.

Step 5: Getting the Ignitor

The ignitor is what the picture shows. The grill lighter has this ignitor inside of it. You will need to use the seam on the lighter to get inside. Use your fingers and pull each side of the seams opposite directions. The ignitor should be located next to the trigger.

Step 6: Creating the Arc

Sadly, I don't have pictures of the arc but, i can explain. First, the arc is the blue spark that is created when pushing the button on the ignitor and creates pressure when the arc and hairspray meet causing the potato to shoot out of the gun. To create this you will take your screws and will use a screw gun. Drill the screws in the pvc pipe, less than an inch apart, or I recommend you do this on a cup first. Now, wrap each of the wires around one screw. Lastly, put duct tape or electrical tape over each of the end of the screws (the part the drill touches). Now that the arc is done, push the button on the ignitor and test out and see the arc. If it doesn't work add more duct/electrical tape towards the end of the screws.

Step 7: Tips

Tips:

Use medium size potatoes. When putting the potato inside the barrel make sure to not push it down too far.
The end of a broom is a good jammer to shove the potato down the barrel.
When buying hairspray, use the kind that doesn't turn to liquid fast.
ALWAYS KEEP THE MALE COUPLING UNSCREWED AT ALL TIMES do to the hairspray drying and making the coupling screwed in permanently.