How to Build Your First Cardboard Robot Arm

Learn how to build a simple, working robot arm using cardboard, string, and your own hands. HowTo: Family Edition: family how-tos that actually help.

1. Prepare the arm segments. Take your four cardboard strips and punch a hole at both ends of each strip. Also, punch a hole in the exact center of each strip. Ask a grown-up to help you measure to find the middle point.
2. Connect the scissor linkage. Overlap two strips and push a brass fastener through the center holes. Do this for all four strips so you have two pairs of 'X' shapes. Then, connect the ends of the 'X' shapes together using more fasteners to create a long, folding chain.
3. Add the gripper. Cut two small 'U' shapes out of your scrap cardboard. Tape these to the very front end of your arm to create a claw that can pinch objects.
4. Attach the string. Tie a long piece of string to the front end of the arm. When you pull the string back toward you, the arm should extend and the claw should close.