Active Time
45 minutes to 1 hour
Total Project Time
45 minutes to 1 hour
Key Concepts
robotics, circuits, engineering
Two example junkbots made from plastic bottles and decorated with recycled materials


Building "junkbots" is a fun activity where you can turn recycled materials—like plastic bottles and cardboard tubes—into robots! This is a great activity for a classroom or a group of friends, because you can race your robots against each other and even make them sumo wrestle. You do not need any previous experience with robotics to build junkbots. A Science Buddies kit is available with all the electronic parts you need, including motors, batteries, and clear instructions for how to connect them. Gather up some recycled materials and get started!


Ben Finio, PhD, Science Buddies
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.


  • Bristlebot Robotics Kit, available from our partner Home Science Tools. The kit contains enough parts to build two junkbots, as well as two smaller robots, called bristlebots. To build one junkbot, you will need these parts from the kit:
    • AA batteries (2)
    • AA battery holder
    • Large motor
  • You will also need the following supplies. These are just suggestions; you do not need to use all of them, and you can pick other materials not listed here:
    • Recycled construction materials, like plastic bottles, cardboard tubes, etcetera
    • Other construction materials, like popsicle sticks and straws
    • Various adhesives and attachment mechanisms, like clear tape, duct tape, rubber bands, zip ties, glue (a hot glue gun is helpful, but adult supervision is recommended)
    • Decorative items, like googly eyes, pipe cleaners, construction paper, glitter, crayons and markers, etcetera
    • Corks (these are pressed on to the motor shafts to make the motors vibrate)
    • Scissors (older students can use hobby knives, adult supervision recommended)
    • Small Phillips-head screwdriver

Disclaimer: Science Buddies participates in affiliate programs with Home Science Tools,, Carolina Biological, and Jameco Electronics. Proceeds from the affiliate programs help support Science Buddies, a 501(c)(3) public charity, and keep our resources free for everyone. Our top priority is student learning. If you have any comments (positive or negative) related to purchases you've made for science projects from recommendations on our site, please let us know. Write to us at


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Active Time
45 minutes to 1 hour
Total Project Time
45 minutes to 1 hour
Key Concepts
robotics, circuits, engineering
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