Empty the 2-liter bottle and remove the cap. Rinse it out with water.
Cut a strip of poster board wide enough to cover the body of the bottle, up to the neck. Wrap it around the bottle and glue it in place using the glue gun.
Roll another piece of poster board into a cone shape. The open end of the cone must be the same circumference as the body of the bottle. Cut the open end of the cone in a straight line.
Press a ball of clay into the inside top of the cone. The ball should be about 2 to 4 oz. to give your rocket some stability. Glue the cone to the bottom of the 2-liter soda bottle.
Decorate the body and nosecone of your model rocket with the markers or paint. You can emulate one of the famous NASA rockets or make an original creation of your own.
Cut four fins any shape that suits your rocket design from the third piece of poster board. Glue them to the bottle near the top. Space them evenly around the bottle. Remember that the top of the bottle will be the bottom of the rocket, so make sure you place the fins the right way around.
Use duct tape to attach the straw to the bottom of your rocket. It will help to stabilize your rocket for take-off.
Use the drill to make a hole in the rubber stopper which is just big enough for the pump needle. The needle must fit snugly. Fill the bottle one-quarter to three-quarters of the way with water. The ideal volume will differ from one rocket to another. Experiment to see which one is best for yours. Place the stopper into the bottle top, insert the needle into the hole you drilled and connect the pump to the needle.
Stick the metal rod into the ground at an angle. Thread the straw onto the rod and balance your rocket on its launchpad. Start pumping -- when the pressure inside the rocket becomes too great, the stopper will shoot off and the rocket will fly.