J. made a robot hand using card stock, plastic straws, tape, and yarn:
When you pull on the end of the yarn the fingers move and curl up:
Here you can see the joints and how they are connected. The orange scribble marks on the green card stock are a little distracting. We recycled a piece of card stock for the project:
This is the robot hand flipped over to show you the backside:
I originally got the idea for the robot hand from the March-April 2007 issue of Home Education magazine, but adapted the instructions. This resulted in a larger robot hand, which is what my son wanted.
I'm not able to provide you with a direct link to that specific article ("Robot Hand" by Kathy Ceceri, who writes the Hands-On Learning column) because it's not available, but I can provide our adapted instructions and you can take a look at these instructions.
Gather the following:
--1 sheet of card stock paper or other heavy-weight paper. Even a thin piece of cardboard will do.
--4 plastic drinking straws (mine were narrow, but the wider width will work, too)
--5 pieces of string or yarn about 12 inches long
1. For the palm of the hand cut a 5 inch square of card stock.
2. For the fingers cut four rectangles 1 inch wide and about 4 inches long and for the thumb cut a rectangle 1-1 1/2 inches wide and 3 inches long. Cut the four rectangles into three equal lengths. These will be the joints.
3. Arrange the finger and thumb joints around the cut-out palm to resemble a real hand. Leave a little space between each joint.
4. Connect the joints to each other and to the palm by taping them together on both sides of each joint, being sure to leave a little space between each.
5. Cut the straws into pieces which are 3/4 of an inch in length.
6. Tape the straw pieces to the backs of the joints, one piece for each joint. Tape a piece to the palm just below each finger joint, too.
7. Thread the string or yarn through the straw pieces and tape the end of the yarn to the tip of each finger. The other end should hang loose near the palm.
When you pull on the loose end of the yarn it will curl the fingers in. J. has had fun making his robot hand try to pick up various objects. He's already devising more sturdy variations using wire and other stuff, so we'll post the updated version when he's finished.