Step 1: The materials you will need.
one Cardboard box (You will need to cut out three wings.)
At least three empty soda bottles (2 litter size)
One role of plastic drop cloth. This can be found at any local hardware store. I used 0.7 mil size (thickness). I would not go much bigger.
One tennis ball
One spool of nylon twine
Tools you will need:
one pair of good scissors
one 12' inch ruler
One spool of duct tape
One hole puncher
you may also want a drill
Step 2: Preparing your rockets engine.
Pick the best bottle for the engine. This means make sure there are no holes or cuts in the bottle. You should never have to cut the engine bottle.
Step 3: The middle of the rocket.
Use the picture as a diagram.
Save the neck of the bottle you will need it for latter!
Step 4: Making wings!
The hypotenuse side should be 6' inches, the adjacent side should be 5' inches, and the opposite side should be 3' inches.
These measurements are what I used, you could test other shapes and sizes to see what fits your rocket best.