Build Your Own Indoor-Safe PVC Air Laucher

 Hiya, Folks!
Today all you projectile fans are in for a treat - I am making a PVC air-pressure launcher that's safe to use inside! It's a great Rainy-Day project. The supplies are easy enough to find (If you have a couple of sizes of PVC pipe), I was able to make it in one day, and when you're finished, it can fire earplugs, mini marshmallows and soft foam "Rockets" up to 20 feet. I know that there are a lot more powerful ones out there, but you can't use those indoors! I hope you enjoy this MakerBot Challenge entry, and good luck making it!
 P.S. I'm sorry if the pictures are blurry, I forgot to set the Macro on my camera! I'll give detailed instructions to help you understand...

   Two lengths of PVC pipe, one slightly wider in diameter
A good pair of pliers with cutting mechanism
   Duct tape - PLENTY of duct tape
An earplug - If you don't have an earplug, get a foam sticky dart - If you don't have a foam sticky dart, get some Styrofoam.
   Some tough scissors
Petroleum jelly, optional
   Medium-thickness wire

 You got that stuff? Okay, nothing's stopping us from building a PVC Air Launcher! Let's get started!

First and foremost, compare the smaller piece of pipe to the larger, placing one inside the other as shown in Pic 1. once you know more or less the difference in size, put a few small patches of duct tape on one end of the big pipe, airlocking it on that side (Pic 2 & 3). Now for the small pipe - wrap duct tape around one end untill you can press it solidly, but not too tightly, into the open end of the big pipe.

  Got that? Okay, moving on to the next step!
  Or if you have a foam dart, go to step 4.
  Or if you have an earplug, go to step 5.

SKIP THIS STEP IF YOU HAVE A FOAM DART OR AN EARPLUG.

  There are two types of projectiles that you can make for this launcher - Styrofoam or Former Sticky Dart. In my opinion, the Styrofoam projectiles stink, but you can use them if you don't have a foam sticky dart.

With an Xacto knife, cut out a piece of Styrofoam (Pic 1) that has roughly the shape of a bullet (Pic 2). Wrap it somewhat tightly with regular tape so it looks like Pic 3, and test to see if it wedges loosely into the "Barrel" of the launcher. If it doesn't make an air-tight seal, wrap duct tape around the inside tip of the "Barrel" and try again (Pics 4 & 5).

Apparently, you don't have a foam dart, so skip on to step 5.

SKIP THIS STEP IF YOU HAVE AN EARPLUG.

  Now for the foam dart - Pull off the sticky tip (Pic 1) and snip the other end into a point, like a rocket (Pic 2). Then, stick some wire into the dart, all the way through, to make it heavier and more rigid. (This will add more distance.) You should end up with Pic 4.
Now press the uncut end of the dart into the barrel of the launcher. You should be able to push it in gently, while still creating an airlock. Too tight? Remove some tape from the barrel. Too loose? Add some tape. It's all about experimentation.

  Once you have the proper seal when you push in the dart, we can go to the next step... Don't worry, I can wait.

  Here's where the petroleum jelly comes into play -
Slide off the big pipe (Pic 1), and spread a coat of the jelly on the duct taped parts of the small pipe (Pics 2 & 3). This keeps the parts working smoothly and greatly improves the airlock. Make sure to do this before each use, when you can.

  That's just about it, so why don't you...

  Once you've built the launcher, you can try it for leaks, problems, and issues.
1. Go to an open space.
2. Pull off the big pipe and gently wedge a projectile into the other end.
3. Line up the big pipe with the small pipe, and
4. Push hard .
  The air pressure created should propel a Styrofoam missle about 8 feet, a foam dart about 15 feet, and an earplug about 20 feet.
    I hope you enjoyed building this - I certainly did!
      Have Fun!
        Win Guy