What you need:
2 plastic cups
1 balloon
scissors
marshmallows and/or pom poms
What you do:
Stack the 2 plastic cups and cut them about a third of the way down. (I used 2 for sturdiness. If you have a surdier cup, one will probably do)
Tie your balloon and cut the (non-tied) end.
Your shooter will look like this:
Place the marshmallow or pom pom on the inside, pull back the balloon and shoot!
