Moving Skeleton Eyes!

How would you like your Halloween skeleton to look at you or follow you with its eyes? This project tells you how to make it happen. I have seen some of the animatronics in the stores with similar eyes but theirs are not adjustable like these. There are a lot of parameters and eye styles to play with which make this a very fun project.

1. Adafruit MONSTER M4SK, available from Adafruit
2. JST 9-pin cable, available from Adafruit
3. Two convex plastic lenses, also available from Adafruit
4. Right-angle USB micro cable, here is one from Adafruit but any one that also passes signal (not just power) is fine
5. Black acrylic paint, small bottles available from Michaels
6. Sharp Exacto knife
7. Wire Cutters
8. Velcro - I used white
9. Foam tape, similar to this from Walmart
10. Hot glue gun. I use a cordless one, similar to this one from Walmart
11. Phillips head screwdriver

In order to work inside your skeleton's cranium, you must first perform a little brain surgery. Remove the two screws securing the skull to the spinal cord. Pop off the skull, then Cut a rectangular hole as a single piece large enough to fit your hand inside.

You should test fit in order to determine if the M4SK eyes line up properly with the eyes in the skull. Probably not. I didn't think so.

Use your wire cutters to remove the nose piece in the middle of the M4SK board. It won't be needed anymore, so feel free to discard it.

While being careful with your Exacto knife, cut out the eye holes in the skull. These holes need to accommodate the clear lenses, so stop frequently and check the fit of the lenses in the eye sockets. After you are satisfied, hot glue the lenses in place and use hot glue to cover any excess holes. Use the black acrylic paint to cover the hot glue so it matches the eye sockets. Next trim pieces of foam tape and adhere to the back of the lenses for holding the M4SK boards.

Connect the 9 pin cable between the two M4SK boards. This is also a good time to power up the board. If you like everything, then fine. If you want to make changes to the eye appearance and behavior, follow the instructions given by Adafruit. This requires plugging the eyes into your computer and editing a configuration file using a text editor, then saving the results back to the M4SK board.

Because the skeleton I own is smaller than a normal person, the M4SK boards do not actually fit within the skull. So use your Exacto knife to cut slots behind the zygomatic bone in the skull to accommodate the boards as they stick out. Go ahead and attach the boards to the foam tape you put on the lenses. Because the boards are white, they really aren't that apparent, despite sticking out of the side of the skull. Certainly not from a typical viewing distance of three feet or more. If you like, use hot glue or your favorite material to hide the boards better. But honestly, nobody will notice.

Attach the micro usb power cord to the board and power up the eyes. This part is finicky, because you are looking at the skull while moving around the boards behind the lenses with your hand stuck inside the cranium. Take your time, stepping back across the room to ensure the eyes line up with each other and also the eye sockets. I probably spent at least 30 minutes on this activity.

Follow the instructions provided by Adafruit here, to ensure your boards are performing to your liking. Have fun playing around with all the different settings. I believe this is the config.eye file that I ended up liking best:

After you finish playing with the eye configurations and placing the skull around the room, your skeleton would appreciate having its head back. Reattach the head using the two screws retained from step 1, then hang your skeleton with its new eyes somewhere spooky. Plug the usb cable into an appropriate power adapter, and enjoy.