How to Build a Toilet Paper Roll Catapult

Get ready to start building with recyclables today! We’re making a super fun and super simple Toilet Paper Roll Catapult. This project is a perfect engineering challenge for young kids or days when you only have a bit of time. Kids love firing pom poms and the simple build means they’ll love succeeding. With just a few supplies and a bit of recycling, pom poms will be flying in no time.

This Toilet Paper Roll Catapult is a fun STEM project for little kids or quick building sessions. Just raid your recycling bin and have fun!

This Toilet Paper Roll Catapult is a fun STEM project for little kids or quick building sessions. Just raid your recycling bin and have fun!

What is a Machine?

This project is a perfect opportunity to learn about simple machines, the building blocks of all things that move. A catapult uses the power-increasing simple machine called a lever. 

Here are the six types of simple machines:

  • Lever: A stiff board that rests on a center turning point called a fulcrum that is used to lift objects. Think teeter totter.
  • Wheel and axle: A wheel with a rod attached to the middle that can help lift objects. Think bicycle.
  • Pulley: Adds a rope to a wheel which allows you to change direction of a force. Think flagpole or window blinds.
  • Inclined plane: A hard, flat surface with one end higher than the other. Aids in moving objects. Think slide.
  • Wedge: Two inclined planes put together and helps push objects apart. Think axe.
  • Screw: An inclined plane wrapped around a pole that can lift objects or hold them together. Think screw.

row of teeter totters

Machines Create Mechanical Advantage

So now you know what kinds of machines there are, why would you build one? Because machines make life easier! They create what’s called mechanical advantage. Mechanical advantage is a measure of how much the force you put into the machine is multiplied into an output force.

The power in this catapult is dependent upon the mechanical advantage of the lever that you build. How high your object flies depends upon a few things:

  • Effort: The amount of force you use when you press down on the catapult
  • Load: The amount of force needed to lift the pom pom or cotton ball 
  • Placement: The center toilet paper roll fulcrum, the load, and effort placements all impact the mechanical advantage.

A lever creates a mechanical advantage, a measurement of how much a simple machine multiplies force. The ratio of effort to load depends upon in a lever's mechanical advantage depends upon the locations of the effort, load, and fulcrum.

Now let’s get building and making pom poms or paper or cotton balls fly! You may need to try a few different placements of the load, fulcrum, and effort to make the highest-flying catapult possible. This is called the engineering design process!

Toilet Paper Roll Catapult Supplies Needed

This catapult uses just a few simple supplies.

  • Toilet paper roll
  • Ruler (or paint stick or other long, flat item)
  • Masking tape
  • Plastic cap
  • Pom poms or other things to launch like marshmallows, cotton balls, balled up paper

ruler tape pom poms plastic cap toilet paper roll catapult supplies

How to Build a Toilet Paper Roll Catapult

  1. Lay the toilet paper roll on a flat surface and tape down securely with masking tape.

tape toilet paper roll to table with pom poms

  1. Make a tape circle and stick the plastic cap to one end of the ruler.

tape cap to end of ruler with a tape circle next to toilet paper roll and tape roll and pom poms

  1. Tape the middle of the ruler perpendicularly to the toilet paper roll.

ruler with cap on end taped to toilet paper roll with pom poms and tape roll

  1. Drop a pom pom or something else soft into the cap and hit the opposite end of the ruler. Watch the pom pom fly!

closeup of pom pom on ruler end of catapult

  1. Turn this build into an experiment by testing the location of the fulcrum, the center point of the lever. This is where the ruler is attached to the toilet paper roll. Does moving the fulcrum change how the pom pom flies?

finished toilet paper roll catapult with pom poms around it

Check out the Toilet Paper Roll Catapult Being Built

Check out the balloon car being built PLUS another fun project, a toilet paper roll catapult, in this video!


More Fun Toilet Paper Roll Activities

Want a more advanced simple machine build? Check out this Toilet Paper Roll Balloon Car.

toilet paper roll balloon car

Or maybe firing pom poms is really your thing :) These Pom Pom Shooters are super fun. We’ve made them three different ways so you can use what you have.

three fun ways to make pom pom shooters

Or maybe you wish you were out traveling these days! Build an Upcycled Suspension Bridge that’s modeled after the Golden Gate Bridge in San Francisco.

toilet paper roll and cardboard upcycled suspension bridge


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