Instead of purchasing a kit or cutting pieces of wood for the project, create your own toy catapult with objects readily found around the house. Rubber bands tie the project together and provide tension for the catapult, while any stick-type objects, such as chopsticks or craft sticks, may be used for the framework.
Arrange four chopsticks or craft sticks into a square shape so the edges overlap a 1/2 inch or so near all four corners.
Wrap rubber bands around the intersections at each corner so the bands act as elastic tie-downs keeping the sticks connected. If the bands are loose enough to wiggle the sticks out of place easily, wrap the bands around once more or add more rubber bands.
Set one stick near each corner of the frame. Wrap a rubber band near one end of each, then connect the sticks to each of the four corners with the rubber bands so the new sticks stand up. Keep the rubber bands fairly loose at this point so the top end of each new stick can be repositioned.
Angle one of the vertical sticks toward another so it creates a right triangle. Wrap rubber bands around the tops of the two sticks to keep them together in the point shape, then add rubber bands along any of the points of the triangle to ensure the sticks stay still under pressure. Repeat the process with the two remaining vertical sticks.
Add a stick to create a horizontal crossbar spanning the peaks of the two triangles. Secure the crossbar tightly with rubber bands. Add a second crossbar 1/3 of the way down along the angled sticks, keeping the crossbar horizontal. Secure it tightly with rubber bands at each end.
Set a stick so one end rests at the center of the bottom frame beneath the crossbar created in Step 5. Attach the stick to the frame at this point with rubber bands.
Secure a plastic spoon to the loose end of the same stick so the bowl faces up. Adjust the spoon along the stick so that if the two are attached to one another and pivoted from the connection point with the base, an object set in the bowl will clear the top crossbar if this mobile arm moves at moderate speed. Connect the spoon to the stick with packaging tape, attaching the spoon either on top or beneath the stick based on personal preference.
Loop the end of a strong rubber band around one end of the lowest crossbar, sliding the rubber band through itself to tie it to the crossbar.
Hold the catapult arm -- the mobile part with the spoon attached -- up against the crossbar. Wrap the rubber band behind it and attach it to the other side of the crossbar, wrapping the band as tightly as possible to create tension for the catapult arm. Test the catapult arm by pulling it back a couple inches and letting go -- if the arm moves quickly, the band is tight enough. If not, add a second rubber band to create more tension, or tighten the first one.
Hold the base of the catapult down. Pull the catapult arm back slightly while holding a ping-pong ball or wad of paper in the same hand. Place the object in the spoon bowl. Release the arm to send the ball flying.