How to Build a Catapult out of Dowel Rods and Rubber Bands

Here’s a great summer project for kids – build a catapult out of pre-cut dowel rods and rubber bands!

Build a catapult to shoot splash bombs or ping pong balls

Over the years, we’ve done a lot of exploring with catapult making!  We’ve built them out of Tinker Toys and tissue boxes, and even just used forks as catapults!  Aidan and I have been on a quest the past couple of years to design a catapult that will launch water balloons.  We were hoping that this one would do the trick, but alas, water balloons are really hard to launch because of their weight and wiggly shape.  However, this catapult shoots ping pong balls and water bombs really well, and building it does not require special tools or a trip to the hardware store!

How to build a catapult out of dowel rods and rubber bands

The design of our catapult was inspired by this post that I found on Pinterest.  I found the photo of the pencil catapult on Pinterest, but the instructions in the post don’t fit with the picture.  I figured that dowel rods might make a bigger and stronger catapult, so we decided to do that instead of pencils.

To make this catapult, you will need:

  • 12 dowel rods – I used pre-cut 12″ and 3/8″ diameter dowel rods that I found at Hobby Lobby.
  • Rubber bands
  • A juice bottle lid or similar object to use as an ammunition basket
  • Low temp glue gun
  • Something to shoot – ping pong balls or water splash bombs.  We also had good success with homemade sponge water bombs

Step 1:  Use rubber bands to make a “T” shape with two dowel rods.  Then add three more rods to make the square base of the catapult, like this.  (If you make the base first, you’ll end up having to take it apart to add the vertical piece for the shooting arm.)

How to make a catapult with dowel rods and rubber bandsStep 2:  Add 1 vertical rod to each corner.  Add a horizontal rod at the top on the side where the shooting arm is.

How to build a catapult out of dowel rods and rubber bands

Step 3:  Add a horizontal rod to the other side, where you should currently have two loose vertical rods.  Put this horizontal rod a couple of inches down from the top.  Then, connect all of the vertical rods at the top, so that your catapult looks like this.

How to build a catapult out of dowel rods and rubber bands

Step 4:  In order to make the shooting arm long enough, we added a second dowel rod.  If you’re not buying them pre-cut, you could just make that piece longer.  However, I figured it was easier and cheaper to buy the pre-cut ones.

We used a long blue rubber band to give tension to the shooting arm.

How to build a catapult out of dowel rods and rubber bands

Step 5:  Glue on your ammunition basket, and you’re ready to fire!

How to build a catapult out of dowel rods and rubber bands.My husband and my almost 10 year old assembled the catapult together.  Aidan could probably assemble it himself now that he knows how to do it.  My husband thought that it was a good project for learning how to wrap the rubber bands so that everything stayed together, since that’s a good life skill to have.   Aidan enjoyed tinkering with the catapult to get it to shoot as far as possible.  He really enjoys engineering type activities like that.

How to build a catapult out of pre-cut dowel rods and rubber bandsExtend the catapult fun with some variables to test!  

  • Add additional or tighter rubber bands.  Does additional torque affect the catapult’s power?
  • Try changing the angle of the rubber bands. 
  • What objects shoot the farthest?  Try ping pong balls, marshmallows, pom pom balls, etc.
  • Which travels farther – a dry splash bomb or a wet splash bomb?
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