Here’s a fun contraption to build out of Lego bricks – a rubber band powered Lego car! Aidan (11) and I have two different versions to show you, and hopefully these will inspire the builders at your house to create their own! This would also be a great project for a Lego club, scout group, or Lego birthday party!
Rubber band powered car #1:
The picture below shows the pieces needed to build this car.
This rubber band car will travel pretty far because of its design – you wind it up, and then the rubber band comes completely loose as it rolls forward, allowing it to travel as long as it has momentum.
The special parts came from the LEGO/Klutz book and set Crazy Action Contraptions. (Amazon Affiliate link) We also used wheels from a basic set and a rubber band. If you don’t have these pieces, hopefully this car design will give you some inspiration as to how the design goes so that you can create a car with what you have. We do recommend the Crazy Action Contraptions book for kids who like to build machines. It comes with some great parts and a book with several projects to build.
Step 1: Attach the two short axle pieces to the gray piece as shown. Add connector rods as shown.
Step 2: Attach the two 10-dot pieces and two wheels to the axle. These will be the back wheels.
Step 3: Add the longer axle and two more wheels to the front of the car. The tan colored connector rods (one in the back axle and one on the top of the car) will hold the rubber band.
Step 4: Build up the back of the car to make it look like the back.
Step 5: Load the rubber band. Wrap it around the front post and the back post, and turn the wheels to tighten.
Let go, and let it roll!
Rubber Band Car #2
This car does not travel as far because of the design. It stops itself when it has unwound to the full length of the rubber band. The benefits are that it does funny tricks and that the Lego bricks in this car are easier to find. It would also be fun to have kids build this version and experiment with changing the length of the rubber band to see the effect on the car.
Step 1: Find two 10 x 1 bricks with holes in the sides.
Step 2: Cover those two bricks with flat bricks. Our flat bricks had holes in them, but that is not necessary. Add a 4 x 1 brick on the front. Again, ours has holes but it’s not necessary.
Step 3: Add more bricks to the top as shown.
Step 4: Connect the two rubber bands “luggage tag style.”
Step 5: Slide the rear axle through the last hole on each of the 10 x 1 bricks. Put on the wheels. Attach the rubber band to the rear axle as shown.
Step 6: Stretch the rubber band around the front of the car and around the top bricks as shown. Do this before you put on the front wheels as the rubber band needs to run under the front axle.
To wind up the car, turn the rear axle. Or, you can actually pull this car back and let it go!
We would love to see pictures of your kids’ (girls too!) rubber band powered Lego car designs! Feel free to share photos on the Frugal Fun for Boys Facebook page.