The Spring-Stick Launcher
A small hand-held launcher that flings a marshmallow across the yard.
STUFF YOU'LL NEED
- • 7 craft sticks (or flat scrap wood)
- • 4 rubber bands
- • 1 plastic spoon or bottle cap
- • Small scrap of cardboard
- • Tape
- • Something soft to launch (marshmallow, wadded paper)
TOOLS
- • Scissors
- • A ruler
- • Your hands
SAFETY
- ⚠ Never launch at a person, pet, or window.
- ⚠ Launch soft things only.
HOW IT WORKS
You store energy by bending the arm. The rubber band pulls it back fast, and all that stored energy goes into the thing you launch.
This is elastic potential energy. A stretched rubber band is a battery made of stretch. Release it and the stored energy becomes motion.
BUILD STEPS
- 1
Stack and band the base
Stack 5 craft sticks. Wrap a rubber band tight around each end so the stack can't slide.
HINT: Wrap in a figure-8 so it grips better.
- 2
Make the arm
Stack 2 sticks and band one end only. That banded end is the hinge.
- 3
Push the base through the arm
Slide the big stack between the two arm sticks, right up against the hinge.
WATCH OUT: Push slowly. Craft sticks snap if you force them.
- 4
Cross-band the joint
Wrap a rubber band in an X where the base meets the arm. This is what makes it snap back.
HINT: Tighter X = more launch.
- 5
Add the cup
Tape the spoon or bottle cap to the top of the upper arm stick.
- 6
Brace it
Tape a folded cardboard triangle to the back so the whole thing stops wobbling.
- 7
TEST
Load something soft. Press the arm down. Let go. Watch what happens.
TEST: Aim at a cardboard box target. Move it back one step every time you hit it.
IF IT ISN'T WORKING
- It barely launches
- Your rubber band is too loose. Add one more wrap.
- The arm snaps sideways
- Add a cardboard brace under the arm.
EXPERIMENT WITH IT
- • Count how many paces it flies. Change one thing. Count again.
- • Try a heavier and a lighter projectile. Which flies farther? Why?
NOW INVENT SOMETHING.
What would YOU change?
