Start by cutting an empty paper towel tube in half. This will give you two pop pop poppers!
Cut your cardstock to size and roll it around the paper towel tube. Having an adult use a hot glue gun glue the paper together. You could skip the need for hot glue but decorating with paint, markers or crayons too.
Take a balloon that is not inflated and tie it with a balloon or simple knot.
Cut off the top portion of the balloon.
Add the balloon to the bottom of the paper towel tube, with the knot facing away from the tube. You may want to add a drop of hot glue or tape to secure depending on the size and material of your balloon.
Fill the tube with mini marshmallows or pom poms. Don't overfill as then it won't deploy properly.
To launch the poms, pull back on the balloon tail and release! When shooting your popper, point slightly up for the best chance of it flying.