Step 1: Get Materials
A Garbage bag or plastic bag (for the parachute)
Cardboard or foam core
A Tennis ball
Dental floss or string
Step 2: Cut the bottles
One bottle you're not going to anything to, which will be your bottom bottle that will connect to the launcher.
The other bottle you're going to cut the top so you have the bottom of the bottle.
Put the bottles together (DO NOT TAPE THEM) to make sure they're cut right before you move on.
(The picture is what the bottles should look like after you attach the wings and make the parachute.)
Step 3: Make the wings
Get the cardboard or foam core and cut out a wing that will a good size for the bottle.
Cut out 3-4 wings that are the same in size. If the size is off it will effect how high the rocket launches. You can make them whatever size you want and whatever shape you want.
Once the wings are cut out, tape them onto the sides of the bottom bottle of your rocket so it looks somewhat to the picture. Make sure they're taped around the same height because the wings effect the direction and the height of the rocket.