A simple engineering project where students build a working robotic hand using straws, string, and a cardboard tube. This model shows how human finger joints bend when tendons pull—perfect for learning basic biomechanics.
Difficulty Level: Medium
Concepts: Robotics, Engineering, Prosthetics
Materials List
- Plastic drinking straws
- Scissors
- Threading needle
- Strong string or thread
- Cardboard tube (to act as the wrist/arm)
- Tape
Steps
- Prepare the Straws:
Cut each straw into small segments. Make tiny notches so each segment bends like real finger joints. - Make the Fingers:
Arrange the straw pieces in a straight line and tape them lightly, keeping the joint gaps free to bend. - Add the Tendon Strings:
Thread a long piece of string through the straw segments using a needle.
This string will act like a muscle/tendon. - Attach Fingers to the Hand Base:
Tape all five fingers onto a flat piece of cardboard or directly onto the cardboard tube. - Create the Pull Mechanism:
Pass the string ends through the tube and leave them hanging out the bottom. - Test the Movement:
Pull the strings - each finger should bend like a real human finger joint. - Fine-Tune:
Adjust tension, trim excess string, and reinforce joints with small tape pieces if needed.
Science Behind It
This model shows how tendons and muscles work in your hand:
- Straw joints act like finger bones and knuckles.
- The string acts like a tendon.
- When you pull the string, the finger bends, just like your real tendons pull your bones to move your fingers.
It’s a simple way to understand biomechanics, force, and mechanical movement.
Watch the video!
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