Tentacle

I want to be able to pull a string that causes the arm to coil. When I release the string, the arm should be straight

My model has five interlocking segments and four points of articulation.

The pieces are held together by pieces of elastic thread.

The model is not moving in the way that I want it to

Wire Hand

Orthographic Drawing

Doctor Bird

Animal Hands

More Images of Hands

This image comes from a page on the Smithsonian website. It has some interesting information:
Smithsonian: Inventing Ourselves

Mechanics of Hands

Da Vinci had some great anatomical drawings of hands that give insight into the inner-workings of them.

When viewed as an extension of the arm, hands become somewhat easier to understand