Pneumatic Rocket From Aluminum Cans

So I was in my workshop one day, trying to make a little air tank I could get up to 10 PSI or more, when I came upon this design. I thought it was very cool and easy, and it doesn't even need fuel!

So you'll need some gorilla (or duct) tape, and two aluminum cans, and a valve stem from a bike.

Punch a hole in the can as in my Instant Sheet Metal Tutorial, just lower in the first can. Next cut the top off of the second can, also as in my instant sheet metal tutorial, just make the cut lower down.

Insert the valve stem into the hole you punched into the first can, then use the gorilla (or duct) tape to secure the valve and seal any cracks (as shown in the picture).

Now just push the second can on top of the first can, and you're done. To launch the rocket, just hook a bike pump up to the valve stem, and pump fast once to launch the rocket!