Instructables member Nathan Sellers has posted a project for building a pair of wooden monster hands and arm extenders for use in a Halloween costume. Using a mechanical hook and wire relay system that is attached to each carved wooden finger joint, the hands are controlled by Nathan’s real finger movements.
This brief movement test video shows what the hands look like in action. Pretty smooth, impressive articulation for three chunky wooden fingers.
For materials, Sellers mainly used stuff he had lying around the house, namely some 2×4 and 2×6 (for the palm) lumber. He ended up buying and using 60 stainless steel eye hooks and around 10′ of picture hanging wire (“mirror cord”) to create the finger actuation system.
I wanted these hands to be large and 3 fingered. I drew out a basic design and figured out the lengths for each segment of finger. I had to factor in an extra 1/2″ for each segment due to the joint system I had set up.
The eye hooks are really what allows the manipulation of the finger. On the back of the finger, they hold the bands in place for the fingers to snap back erect. On the inside of the finger, they hold the wire which, when pulled, curls the finger. On the backs, a hook is placed on either side of the joint. On the inside, a hook is placed toward the top of each segment. This creates maximum leverage.
This is where artistry meets functionality. I wanted the fingers to look more natural while also providing maximum mobility. I used my Dremel tool for this. This took the fingers from looking really blocky to being more like actual fingers. This took quite a bit of time.
Now with everything put together, the mechanics are ready to be put in. I started with the wires. I ran the wire through the eye hooks and then tied it to the top hook. The bottom of the wire is tied to the key ring. The measurement of this needs to be right for where the hand is to get the right amount of finger curl with your own finger.
Here’s the amazing 7′ monster he turned himself into using these arms. You can find the details of the full monster costume project here.
You can see the full Mechanical Monster Hands Instructable here.