In five minutes, you can build an air-powered bazooka. The bazooka launches plastic capsules about 100 feet. And with some tweaking, you might stretch that distance quite a bit.

Although everything you need to know is in the pictures, the video tells the whole story just as well…

If the video is not playing, have a look at it here...

All you need to know to build this low-pressure kid's gun is described in the texts, as well as in the comments with the pictures. Have fun building and shooting! But please be careful, don't point your self made bazooka to living creatures.

Step 1: Stuff You Need

Stuff you need:

A vacuum cleaner. Any model will do.
Straight piece of PVC tube, at least 1 meter long. Longer is better (see the text on tweaking)!
Inner diameter 35 mm (1.4").
A PVC 3-way junction with an angle of 45°, that fits the straight PVC tube.
Duct tape.
A projectile: I used the plastic capsule that is inside "surprise-eggs" (see picture). Old school film containers work as well. Whatever you use, make sure that the projectile's diameter is just a little smaller than the PVC tubes'.
A small piece of cardboard (business cards are perfect).

Step 2: Make It

Attach the 3-way junction to the straight tube, using duct tape (you can glue the parts with PVC glue, of course, but there's no good reason to do so).
Wrap duct tape around the tip of the vacuum cleaners' hose, so that it fits snugly into the slanting tube. This fit should be as air-tight as possible.
Push the vacuum-cleaners' hose into the slanting tube of the pvc junction part.
Test whether the projectile can run smoothly through the assembles PVC tubes, when the vacuum-cleaner is attached.
That's it :D

Step 3: Lauch It and Tweak It

Launch it:

Power up the vacuum cleaner.
Cover the tubes' ending with the PVC-junction with the business card. The vacuum cleaner will now suck air from the other end of the PVC tube.
Hold the projectile firmly, and insert it in the air-sucking tip of the pvc tube.
Let go and enjoy!

Tweak it:

If you extend the straight pvc tube, the projectile will be accelerated over a longer period. And so the projectile's velocity will increase. So extend that piece of tube!
Add some weight to the projectile. We filled the capsule with rice, but sand might work better. Experiment to find the right weight for the projectile.

Again: Have fun! Don't shoot in the direction of living creatures, though. So be careful, too.