Picture of Animatronic Tentacles with Arduino
***Disclaimer***This instructable is documentation for a work in progress. Although the project is not yet complete, it has reached a place where I believe it can begin to be beneficial to other makers.

The concept for this project was spawned when a friend suggested I be Slenderman for Halloween. When I first looked at pictures, I wasn't terribly excited because I am a prop builder more than a costumer, and Slenderman didn't have any props. However, I then discovered that in some depictions he has tentacle-like appendages emerging from his back. I started scouring the internet, seeing if anyone could give me any advice on how to bring this part of the costume to life. To my dismay, the best I could find was suggestions using armature wire to support the tentacles, but they wouldn't move so I set out to design my own.

The Overall Plan:

-Include 4 or 6 Tentacles

-Be mounted on the back

-Be controlled with 1 or 2 Arduino's using 2 Wii Nunchucks

-Move automatically when not being actively puppeteered

-Have an option to fold tight for moving around tight spaces
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Step 1: First Draft: Tail - Part 1

Picture of First Draft: Tail - Part 1
In most cases, small scale is usually the way to start a project. For this, however, it was too hard to visualize how everything would work, so I started work on a single, large scale model. Since there would only be one of these, I decided to try to build a tail that had the same functionality that the future tentacles would have. The idea was to use PVC pipe as the "spine" of the tail, and have laser cut 1/8" MDF disc's as the standoff's to make up the vertebrae.

First, I designed the standoff's in Corel Draw. The large hole in the middle was for the PVC and the smaller four holes for the control cables. I then printed these pieces on an Epilog Legend Series laser cutter. It took some experimenting to get the sizing right, and in the process I created an unbelievable number of these discs.
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jhall302 years ago
Great project! I would suggest a couple of things, though.

1. Instead of two Arduinos, consider using just the ATmega chips, as they are far less expensive, and use the same command set (you can buy them with the Arduino boot loader already on them). I use an Arduino to program the ATmega and ATtiny chips, which greatly reduces the cost of projects.

2. I would try to add more random looking ambient movement to the tentacles. Use a defined range, and slowly transition between two random points within that range for each servo on a tentacle. For fun, randomly choose a delay time, as well, so that some tendons stay in their positions for longer than others. Make sure that this is also constrained to a reasonable range.

I love the work you've done, and the ideas you've come up with!

Think of fabrics for the skin. There are many options that are rubbery in appearance, and they'll cost less than silicone. They may weigh less, too.
thejuggler (author)  jhall301 year ago
Thanks for the great response jhall30! Now to my replies:
1. I have looked at this, and for the final version I think I might. I am also working on an Arduino Segway at the moment (Instructable to follow), which might be able to use the same idea. I have seen tutorials on how to program the ATtiny with an Arduino, but not an ATmega. If you have any resources on doing that I would love them, thanks :D

2. OOOooo. That's cool! I like that better than just sweeping between the extremes! Thanks for the Idea!

As for the fabric, I've looked at it but my sewing ability is near 0. Though swimsuit type material is starting to sound better after the fiasco of making the test skin. (My dad wasn't too happy with the mess I made in the garage)

Thanks Again!
sorry to ruin any visions of having the first ghetto arduino segway but johndavid400 already made one and its in his book. on the other hand you could just buy his book, follow all or some of the instructions and end with a segway. either way good luck and even if you just follow the instructions, the site could use another organized thoughtful instuctable like this one.
thejuggler (author)  awesaomeness511 months ago

Hi Awesaomness5,

I make no claims to my Segway being the first, there are dozens of them on the internet and I have drawn heavily from the information they learned and shared while building their projects.


1. You can use an Arduino itself to program your ATmega328p chip, and then pop it out and put in another. It already has the socket for it, unless you're using the SMD version. After all, that's the chip it comes with. If you get them online with the bootloaders already installed, they're plug-and-play in the board. The chips are around $2-3 online through some retailers. It's almost not even worth looking at the ATtiny chips, unless you really want to save space.

2. Yeah, I've had some luck with that technique in some projects. It keeps things reasonable while appearing random. I usually pick a base, then add a random number to it (which has been mapped to my "reasonable" range). I suppose you could just map the number directly to the range without the addition.

3. Sewing shouldn't be that difficult. It'll mostly be a straight line up until the end of the tentacle. Just sew it inside-out, and then invert it and slide it on the tentacle. Get a friend to help if you have a sewing whiz around. I'm lazy, of course, so I use a laser to cut fabric.
jaybo20991 year ago
Pull some women's panty hose over the device for a skin. Then coat the panty hose with layers of liquid latex. You can also use pieces of tissue paper and unrolled cotton balls with the latex and build up different textures on the device.
thejuggler (author)  jaybo20991 year ago
That is an interesting idea, I have never worked with liquid latex so it would be a learning experience. But, then again, so has this entire project.

It's super easy. You can add a touch of acrylic paint to color it and you simply paint it on in thin coats. You end up with a great rubber surface that won't crack. At $55/gallon it isn't as bad as silicone either.

Drake23123 months ago

Hey i was wondering, would you be able to do what you are doing with the wii nun-chucks with an EEG device? if your not sure well that's ok but if you think it's possible could you message cause i plan on doing this and wearing it at one of my schools carnivals on my last year there, thanks for any info

danielepoi3 months ago

Hi. GREAT TUTORIAL! Well explained and interesting subject. I am trying to make a tentacle of sorts but i'm not sure about how you joined the servo motors to the cable. Do you have an photo or graph for that? It would be very helpful if you could publish one. thanks heaps!


looop454 months ago

Give us an update. Even if it is a small one.

Nightrose135 months ago
Hey just wanted to ask.... How much did this cost? I want to do this for squid girl!
Darkfur1 year ago
Nice, now I have a hardware guide to go with my software!
thejuggler (author)  Darkfur11 months ago

You had software lying around for this?! I'd love to get a look at it sometime if you wouldn't mind.

Darkfur thejuggler11 months ago
I can dig it up if you want...
thejuggler (author)  Darkfur5 months ago

That would be great. Why do you have software for this?

I intended to build a backpack for a slender man costume for halloween, complete with pseudorandom flailing tentacles. Though I never got around to it.

shadowopal1 year ago
Howdy. Been following this for a while and am curious how the project is coming. Going to start using your project for 2014 Halloween.
thejuggler (author)  shadowopal11 months ago

Hi shadowopal,

The product has been put on hold for a while for budgetary and time concerns. I ran out of money to invest in it (poor college student) and I entered college. I hope to pick the project back up when I get the chance and will update this page as soon as the project get's back underway. Good luck with your build!

Juggler, maybe we can help each other. My biggest challenge will be acquiring the vertebra and creating a backpack mount as I don't have access to a shop or 3d printer.

If you are able to assist me with that, PM me and let me know how much of a gift$ you would like (beforehand) in exchange.

SergioFromTX6 months ago

Thank you so much for this. This is inspiring. I just purchased the Stan Winston Tentacles video and am going to watch this and start planning for Halloween 2014.

If you had to provide a very rough guestimate of how much the tentacle setup will cost (per your design here), what would that be? $50, $300, $1000, $5000? Again, I know there are a number of variables regarding cost, but I'm just wondering what I'm considering getting myself into. Cheers!

JoCu641 year ago
Fascinating project - re skin material how about this LDPE tube netting Commonly used to package & protect delicate items like bottles etc. Should be light, stretchable and add a bit of texture. May also be possible to fit over a tapered former and dipped into liquid rubber to fill voids.
thejuggler (author)  JoCu6411 months ago

Neat Stuff! I will take a look at it. Early on I considered the jacketing stuff they use to make large cable snakes. (Sorry if that doesn't make since, I don't remember what it was called) This product looks simpler and more flexible.

mmontemor1 year ago

I have laughable experience on arduino builds on general but could you clarify some doubts? I intend to build something very similar to this project of yours, but with a tougher structure that can, at least I hope, serve as an automated arm to hold things and stuff. Yeah, Dr. Octopus style.
Do you think I could do it just by adjusting your build? New materials and stuff.

thejuggler (author)  mmontemor11 months ago

The Arduino is a pretty powerful platform, and I have yet to be disappointed by what it can do. To drive a robotic arm of that strength you will probably need to beef up the circuitry with an external power-supply and something like an H-Bridge to drive the motors. I'd love to see how your project works out!

thejuggler (author)  instructamaker1 year ago
mae-kitty1 year ago
What is that black joint piece you are using? Did you create it or buy it? If so where from?
thejuggler (author)  mae-kitty1 year ago
It is a Cord Grip Strain Relief Connector. I bought it, I don't have the URL handy but I will look it up and add it. It's designed use is to waterproof electronics enclosures and to hang cords from ceilings. They are commonly metal and at minimum a quarter inch internal diamater, so I had to dig for a while to find one this small and made of plastic. (The man at the local home depot said that no such product would exist anywhere, I showed him :P )
You sir are awesome, Ive been making an animatronic tail, I used a compression spring to be the spine between each vertebrae. it worked really well but didnt work very well once i put a sleeve over it.
thejuggler (author)  mae-kitty1 year ago
Thanks for the compliment, and the spring sounds like a very neat idea. Maybe a thinner sleeve would help?
Beenay252 years ago
I think I just soiled myself! This is amazing! I HAVE to try making these...
How are you attaching the servos to the cables?
thejuggler (author)  Beenay251 year ago
Okay I have now tried this without the pulley wheel thing, ultimately it didn't work. A combination of too little torque and too little motion. On to plan B... (which I will let you know of as soon as I figure it out)
I think you could get the pulley thing to work if you were to use very strong servos (I just found some on ebay that pull a whopping 17kg) and fixing the cables to the furthest point of the pulley.
thejuggler (author)  Beenay251 year ago
I am still working that out, get back to me in a week. :) Basically I need some kind of pulley wheel that will be mounted on the servo.
Krayzi991 year ago
Oh, Slendy...
thejuggler (author)  Krayzi991 year ago
jgmrequel1 year ago
Regarding standalone Arduino ATMega chips, the Arduino website tells you how to not only program chips on a breadboard, , but also how to burn the boot loader onto a chip, .

For the skin, you might consider buying latex sheeting. It can a bit pricey, 15~30 a yard, but it has quite a bit of stretch to it, and construction would just be to use rubber cement to bond the pieces together.
thejuggler (author)  jgmrequel1 year ago
Latex sheeting is a really cool idea, I didn't even know it existed. I will definitely be looking into this option, thanks a lot! :) (also thank you for the Arduino links)
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