Build a LEGO Slingshot Car

Here’s a fun new LEGO building idea that kids will absolutely love! Construct LEGO cars that race across the room. This is a great STEM challenge, too.

The mechanism for this car is a little different than the one in our LEGO Rubber Band Powered Car. With the rubber band powered car, you wind up the rubber band mechanism inside the car and then let the car go. In this project, you pull the car back using a rubber band and a launching base, and it zooms forward in the same way a slingshot would launch a projectile. Both projects are so much fun and teach different things about mechanics.

This LEGO slingshot car is a great project for a STEM class or a LEGO club because the parts needed a very flexible. Kids can build the cars any way they want!

Inspiration for this LEGO project came from this Popsicle Stick Slingshot Car on STEM Inventions. Check out their site for a cool non-LEGO version of this project. They also have a kit available with the supplies needed to build the popsicle stick car.

LEGO Bricks Needed

As I mentioned above, you can pretty much use whatever bricks you have for this project!

However, I would really recommend using the narrow wheels shown. If you’re ordering on Brick Link, there are two elements to get:

Technic wedge belt wheel (pulley)

Tire Technic wedge belt wheel

As I mentioned in our LEGO Egg Cars post, this type of wheel really cuts down on friction and makes the cars travel faster and farther. Very helpful with LEGO science projects like this!

To attach the rubber band, we used a 1 x 4 light gray plate with bar arm down. But there are multiple ways to attach a rubber band. Have kids brainstorm with the bricks they have!

We attached the plate to the underside of the car and then attached the rubber band to the bar like you would attach a luggage tag.

The base of the car is built from two 1 x 12 Technic bricks connected with plates. The two red Technic bush on each axle keep the axle from sliding around too much. You want the wheels to be close to the body of the car, but they shouldn’t touch the body and create friction.

Also, if you build a handle on the back of the car, it will be much easier to pull back and release!

To operate the car, you’ll need to build a LEGO launching base for it. Grab a 32 x 32 baseplate and some tiles.

The tiles do NOT need to all be the same size and color. I bought a bunch of 2 x 4 light gray tiles for our LEGO Foosball Game and we’ve been using them for tons of projects ever since! But you can use whatever sizes and colors you have. The important thing is to build a smooth track for the wheels to travel on.

Then add two 2 x 2 round plates and a 2 x 2 round tile. This creates a post to wrap the rubber band around.

How to Launch the LEGO Slingshot Car

To operate the car, place the rubber band around the post. Then pull back! And let go!

Here’s a cool video demonstration for you. Click the play button to watch the video.

NOTE: The center of the car needs to be high enough off the ground that it won’t hit the post on the base! It should roll right over the post without touching it.

The car zooms away with a lot of power! This is really fun to play with.

Add some STEM Learning to the LEGO Slingshot Car Project!

This project is great for demonstrating potential and kinetic energy. When you pull the car back, the rubber band is storing energy (potential energy). When you let go, that potential energy is converted to kinetic energy (the energy of motion).

You can also measure how far the cars travel. Or compare different types of wheels and see what the effect is on distance traveled.

Or try comparing different sizes and thicknesses of rubber bands. Does a rubber band with more tension cause the car to travel farther?

Need more LEGO STEM ideas? We’ve got engaging STEM building challenges!

Check out these 10+ Must-Try LEGO STEM Projects!