All you need is a few items and a mousetrap and build a catapult in about a minute. What you need to prepare a Mouse Trap, some Pliers, a Spoon, a projectile, some wadded tape and paper. and some electrical tape. Using a pair of pliers remove the trigger arm and the trigger mechanism from the mousetrap. Leave the big square swing arm and it's spring. Insert the spoon into the mousetrap with the spoon facing down. Tape the spoon to the metal bar using the electrical tape. Make sure the spoon isn't lodged under the spring move it forward a little bit if necessary.then tape the whole thing to perfectly stabilize the spoon movement (swing). Carefully hold it upright so you can tape around it. Once this is done you are ready to put a soft and safe projectile in the spoon, crank it and fire away.