Things You'll Need
Instructions
Glue each half-round Styrofoam base to each end of the cardboard. Use plenty of glue around the edges of the base so that it does not "chip off" over time with use.
Create supports for the launcher. Using one of the dowels, create a hole in both Styrofoam bases in the center of and half of the depth of each. Pour a small amount of glue in each hole. Insert a dowel in each hole. Allow the glue to dry completely before you move on.
Create the cup for the launcher. Cut the bottom one inch from the Styrofoam cup. Discard the top portion.
Install large paper clips onto the launcher. Open the first prong of each clip. Insert the opened prong into opposite sides of the Styrofoam cup. Bend the prong inside the cup upward to keep it in place inside the Styrofoam cup.
Wrap each rubber band to the wood dowel supports. Take the rubber band around each dowel. Open the rubber band and pull the other end though. Pull tightly to secure.
Attach the free end of the rubber band to the paper clip on the outside of the Styrofoam cup.
Test your launcher. Place the ping pong ball inside the cup. Place your hand on the cardboard and pull the cup back, stretching the rubber bands. Release the cup. The ping pong ball should fire off into the air.