How to Build a Simple Cardboard Robot Hand

Learn how to build a working mechanical hand using cardboard, string, and straws to understand how tendons move your fingers.

1. Trace your hand. Place your hand on a piece of cardboard and trace around it with a pencil. Make sure to draw a wide base at the bottom so you have a handle to hold onto.
2. Cut out the hand. Ask a grown-up to help you carefully cut out the cardboard hand shape you just drew. Once cut, use your ruler to draw straight lines across each finger where your knuckles are.
3. Add the tendons. Cut your straws into small pieces, about one inch long. Glue or tape these straw segments onto each finger section, leaving a small gap at the joints so the cardboard can bend.
4. Thread the strings. Tie a large knot at the end of a long piece of string. Thread the string through all the straw segments on one finger, starting from the fingertip down to the palm.
5. Test your movement. Hold the cardboard handle at the bottom. Pull on the string hanging from the palm, and watch as your robot finger curls inward. Repeat for all five fingers.