How to Make a Lego Catapult with Bricks You Already Have

This LEGO catapult design uses common LEGO pieces that you have already or could substitute a similar block. Kids of all ages can use the simple LEGO catapult idea and make working catapults at home or in the classroom. This simple STEM project is playful learning at its best!

Homemade Catapult DEsign

Last week my family visited a Genghis Khan Exhibit and saw a real life size trebuchet that they could put their hands on (and shoot some ping pong balls across the museum).  At home, they have been all about creating catapults out of everything.

Related: 15 more ideas how to make a catapult

This LEGO catapult design was created by my 10 year old using just the bricks we already have.

The boys own one of the Lego Castle sets that includes a catapult. Many of the pieces used were from that set.  He has modified that a little to increase projectile distance.  

As with all things Lego, modify these instructions to use pieces that you might have at home!

How to Make a Lego Catapult

Step 1  

Construct the base.   The base platform and the catapult foundation consist of these pieces:

Step 2  

Add Lego blocks that allow for arm movement.  

The base built from pieces pictured above are on the left. The pieces used for the arm movement base are pictured on the right:

Step 3

The base is now complete.   

You can see that the two small 2 x 1 stud bricks in between the gold caps are on a rod and can be rotated 360 degrees at this point.   This is where the moving arm will attach:

Step 4

Build the catapult’s moving arm with the pieces shown here or similar:

Step 5

Finish the arm and attach it to the 2 x 1 bricks mentioned above:

Step 6

Attach a rubber band.

Step 7

Launch projectiles across the living room.

Catapult vs. Trebuchet

The exhibit was calling this type of catapult a trebuchet.

We were wondering what the difference between the two weapons were and after a little internet search which included Wikipedia, this is what I understand to be true:

• Catapult:   A catapult is a mechanical device used to hurl objects.   It is a general term and there are many types of catapults.
• Trebuchet:   A trebuchet is a type of catapult.   The early models were called traction trebuchets and used manpower and ropes to launch a projectile.   Later models used pulleys and counterweights and improved the accuracy of aim significantly.

The type of catapult we just built out of Legos could be described as a traction trebuchet if you imagined the rubber band to be men pulling on ropes.

Looking for more trebuchet and catapult building ideas? 

MORE CATAPULT MAKING FUN For Kids of All Ages

• How to make a catapult out of popsicle sticks
• Simple DIY catapult design
• Larger launching catapult design using wooden spoon
• Make a Tinker Toy catapult

More LEGO Fun from Kids Activities Blog

• Our favorite LEGO ideas for kids…and beyond!
• Best LEGO storage ideas for organizing and storing the little bricks.
• Become a LEGO master builder.  It is a real job!
• How to build a Lego table…I ended up building three of these and they lasted for YEARS of LEGO building fun.
• What to do with used legos.
• Make your own LEGO travel case for fun…
• Where are legos made?
• If you liked making a lego trebuchet, then check out how to make a scale out of lego bricks!
• Here are 5 fun ideas to do your own lego challenges for kids.

How did your lego catapult turn out?  How far can you launch projectiles across the room?