Need help with bionic eye

For halloween this year, I'm thinking of doing a costume of Mad Eye Moody from Harry Potter:

The costume is easy enough, but it really needs a working bionic eye to complete it. This is where I need some help.

I think the concept is simple enough. Id use half of a ping pong ball for the eye attached to 2 servos (one for up/down, one for left/right). The issue is mounting the servos and attaching them to the ball. I'm not quite sure how to accomplish this, keeping in mind I have to wear this "eyepatch" contraption.

I found this tutorial for a randomly moving bionic eye, which is what I want. But I can't use this guide for a few reasons:

  1. Its using a trinket, not an arduino. I dont know anything about trinkets, so Id prefer to stick with what I (kind of) know in Arduinos.
  2. It uses 3d printed parts. I know nothing of 3d printing, so not even sure I could find somewhere to make what I need, if it would be expensive or not. This may be an issue I can overcome with a little research though.
  3. 3d printing the above mentioned parts means the eyeball bulges out significantly (see the pic in the tutorial), which isnt the look Im going for. So something needs to be modified. Maybe the ping pong ball needs to be cut smaller than a half and the "movement" of the eye would be reduced a little. Id be fine with that, if the overlook was more consistent with the photo of Moody at the top of my post.

So to recap, I can write the code to do a few simple servo sweeps to create the eye movement, but what I'm really looking for is some guidance on how exactly to mount/attach everything together into some kind of wearable piece. I can certainly add straps, and the ring around the eye, I'm specifically looking for the servo attachments and a possible "housing" for everything, if necessary. I'm not averse to 3d printing anything, but I'm a complete noob so Id need guidance on that aspect as well.

Any thoughts/ideas? Or any other tutorials or guides anywhere on how to rig something like this up? Any advice would be greatly appreciated! Thanks so much in advance!


Use flexible cable/fishing line to pull the eyeball through tubes that are threaded in the rims.
The actual servos and arduino + battery pack can then be worn elsewhere.

Yeah. Definitely build this over some form of safety eye glasses. You only get one set of real ones.

I was just going to suggest that, but since you beat me to it, may I suggest His staff for your costume. A little pricy though.

This is really cool! Id love to have a staff but I may have to use a more generic one due to cost. I do plan to purchase a replica of Moodys flask however, as I think that may be a little more iconic, and relatively inexpensive. Plus I can use it for its intended purpose as well during the halloween party :wink:

Use flexible cable/fishing line to pull the eyeball through tubes that are threaded in the rims.
The actual servos and arduino + battery pack can then be worn elsewhere.

Interesting, I hadn't thought of this approach. Do you happen to know of any diagrams/photos of something like this to help illustrate how it would be set up? I get the overall idea, but would love to see some details. One of this biggest questions I have at the moment is how the half ball "eye" would get mounted so that it can rotate on 2 axes. Ill have to do some research on that, but would still love to see some details about fishing line/tube setup.

I would highly recommend some sort of backer to protect your real eye.

And yes, I definitely plan to have a protective backing layer. Nothing is worth risking safety.


2 axis gimbal eyeball

Ive seen that, and I like it, its simple, but Im worried about the implementation not looking right. Id have to mount that whole thing inside some kind of housing thats supposed to look like Moody's eyepiece, but I feel like it would be way too big. The gold ring that the eye is set in would interfere with the gimbal's up/down rotation, unless I made it bigger to accommodate. Then it becomes too big, and also possibly unwieldly to wear as well. Im struggling to come up with a way to mount and wear everything but still have it look like the character....

Guess Ill have to think about it. For now Im building the exact adafruit tutorial I posted earlier, just to have a physical working example in front of me to start. Hopefully I can just modify it to have the eye be a little less "bulbous" and more inset, that would be ideal. We'll see, I have the parts being 3d printed now, and some other components are ordered and on their way, so maybe by this weekend Ill have an idea of what to do...

In any case, I do appreciate the example. Im just not a great visualizer of a final product. Thats why Im here, trying to learn how to build projects into final form starting with just ideas.