Introduction: Cerberus (3 Headed Dog)

This is a Halloween prop I decided to build after seeing the three headed dog that Spirit Halloween had the previous year. I liked the concept of their prop but didn't like that it only consisted of the heads and front paws so I chose to try my hand at it and build a full bodied dog. This is the results of several months worth of trial and especially error :) It turned out to be quite the adventure but I'm pretty happy with the way it turned out and hopefully you will be too.

Step 1: Starting With the Framework.

For the start off I wanted to build the frame including the legs and spine to do so I got the following supplies:

2 x 12" 5/8 all thread

2 x 18" 5/8 all thread

12 x matching 5/8 nuts

3 x 1/2 square tubing in 4' sections

4 x small hinges

Now I began with 2 of the square tubing pieces and cut them into quarters to make 8 1' pieces. On one end of each of them I welded one of the 5/8's nuts. On the opposite end I welded on the hinges connecting them in pairs. Now we have four pieces with hinged "elbows" in the middle. These are our legs. Now we connect the legs into pairs by threading on the 12" all thread to one end of each leg just far enough have it fully threaded through the nuts. With that done we now have front and rear legs. As for the spine we'll take the last tubing and cut it down to a 3' section and welded it dead center between the two 12" all threads. Last part of this initial step we are gonna thread on the 18" all thread between the "feet" of the legs. You'll want to center it as much as possible then thread on the last four nuts on the outside and close to the legs. I will take a moment here to admit I lost my pictures of it at this stage some how so I drew up a quick diagram of how it all went together and what you should have at this point.

Step 2: Building the Neck Assembly.

I set the frame aside for now and threw together a wire frame cube with some small metal rods I had laying around. This could be made out of wood also if it's easier for you. The key is to keep it small enough to fit inside a reasonable sized rib cage for the dog but big enough to fit three 12v automotive door lock actuators. The actuators can be purchased pretty cheap on ebay I usually buy them in half dozen packs or more just because they come in so handy for props. I welded on three short chunks of angle iron to the front of the box and used them for mounting plates for the actuators. Now here is where my first error came in my usual trial and error method of building things. Originally I had planned for the heads to pop up and down as they barked so I welded three "necks" from 1/2" flat steel rods at about 8 inches each to more small hinges then welded the other side to the cube. After which I connected the necks to the actuators via bicycle brake cables and tested it. Fail! turns out the actuators would work with the necks alone but with the weight of the heads attached they just couldn't lift it so I bailed on that feature for now. Switching the plan up I chose to weld the necks in place to give them plenty of strength and left the brake cable zip tied to the necks to use to operate the jaws instead. The picture shows the finished assembly after I welded over the hinges to make the necks permanent. There is also a picture of a close up to how I connected the brake cable to the actuators. Thanks to all the "adjustments" that had to be made it isn't too pretty but it functions well and will be covered up anyway so ugly works.

Step 3: Let's Make Some Heads!

Okay so kind of a lot happens here in this step so there are a lot of pictures and one video to hopefully give you plenty of visual reference. To start I had to have some skulls to work with so after lots of searching I decided on these. The first pic shows the actual resin cast skull. It is of a grey wolf. They were not too cheap to be honest but they were the cheapest I could find with any decent quality and life size available. Obviously I ordered three of them. In the second picture you see the cotton That I used to shape the flesh later on. We found a big box of this stuff at a cosmetic store pretty cheap. Before I could get into the good stuff I needed to do a little prep work on the skulls so I drilled several small holes in each skull. The next two pictures illustrate the purpose for these holes. One I just ran a small bolt through the lower jaw bone close to the rear of the the jaw. This is where I attached the other end of the bicycle brake cable and is where the actuators pull the jaw down to open the mouth with each bark. Next I attached a simple spring to each side of the skull connecting the main skull to the jaw bone. That was just so the mouth would close on its own after each bark. Next pictures show the skulls attached to the necks and show the cable and wiring I used.

With that all taken care of it's time for the cotton and latex to put some flesh on those skulls. This was a lot of fun honestly and I would have liked to make the entire dog using this technique but I was running out of time and that would have taken forever.

So I took my first skull and jumped right in after watching a video on youtube about how to make a charred human skull. Basically all there is to it is brushing some latex directly onto the skull as a base then lay some stretched out cotton over it and paint more latex over the cotton. I did this to create one full base layer on the skull then let it dry then went over it again slowly adding a little extra in areas I want to thicken up like around the eyes. This process took me about a week or two to do all three skulls but it only takes about 15 minutes or less depending on what stage I was on at the time then I'd have to wait a while for it to dry. There are several pictures showing this happen in multiple stages. For the ears I used toilet paper rolls that I basically just cut diagonally then cut each pair a little different angles so they wouldn't all stick up the same. Then I latexed them on. I did have to hold them in place a while to let the latex dry enough to hold it in place. Later I layered the ears with a little cotton also to thicken them up and mold them into the skull better. As a bit of an after thought I realized I didn't come up with any plan for the eyes but after a quick look around the internet I found some large marbles that I liked and ordered 6 of them and about a dozen 12v amber LEDs. when they came in I hot glued the marbles into the eye sockets and hot glued an LED behind each eye so they could light up which is what the wiring you see in the pictures were for. Now with the eyes in place I used the latex and cotton to build up eyebrows and the look of eyelids. Also I took a little time to make the cheeks a little different each time by sticking something in the mouth to hold it open then latexing the cotton across the jaws in different ways. Sometimes I used the cotton spread out in sheets and sometimes I just used small strands to give the cheeks tears and gaps.

Once all that was done and dried up it was time for paint. I went and got some basic acrylic paint you could find at any craft store. I grabbed several different shades of reds and browns then watered down a little of each color and painted over the whole skull then wiped it off with paper towels then repeated the process over and over again. Doing this made for a great effect because each time I did it the latex would hold just a little more of the paint so I was able to change colors as I deemed necessary and kind of sneak right into the final outcome. It allows for a very nice cushion for error which is always a plus with any project. after the paint dried it was a done deal so I simply used a couple screws to secure them to the necks and that was that.

The last couple pics show the finished mechanism with the LEDs lit up.

As a side note. There is one more step I recommend taking at this point. I found later on that what little gaps around the eyes that didn't get sealed well enough with latex would leak fog and look weird. So what I did to fix this real quick was just lay down some hot glue to fill the gap and to my pleasant surprise it actually looked amazing. The hot glue is clear yet shiny enough to really add some lifelike glint to the area around the eyes. I didn't actually do this until after the entire prop was assembled and I was testing it but it would probably be easier to just do this while you have to skulls on the table after you paint them.

Step 4: Time for a Big Step.

Here I was ready to start bringing this thing together. I managed to score a pallet from a friend and used it as the base for the dog. The idea was to make it look like the Cerberus was guarding the entrance to a suspension bridge to hades. So 2x4's and a little rope was used to make hand railing once the frame had been bolted on.

I'm lucky enough to have a lot of people to give me random scrap metal which is why I chose to make most of it from metal. I bolted the body frame to the pallet using some channel iron I had laying around. Now I put hinges in the knees of the legs because I wanted to make the dog crouch and jump up when activated so I had to do a little more framing to make this happen. The pictures show what I added to the frame bottom under the pallet but it probably looks like a rats nest to everyone but me so I added the new additions to the previous sketch minus the pallet to help illustrate whats happening here.

With the dogs frame securely mounted to the pallet it was time to add a couple features to help create the crouching effect. The plan I came up with was to use trampoline springs to pull the dog up to full standing position quickly, and a 12" 12v linear actuator to push the dog back down to crouched position. But to hold the dog in crouched position long enough for the actuator to back up out of the way for the jump up I used a 12v electromagnetic door lock. I ended up using two springs because one didn't jump him up as fast as I liked. I mounted them from the lower framing to the pallet as shown above. The door lock I mounted up front. It did take quite a bit of adjustment to get the magnet (which was mounted to the pallet) to meet up evenly with the strike plate (which was mounted to the front lower framing) but eventually I got everything just right.

In the end I did need to raise the pallet a little to accommodate the door lock so I just bolted on a couple 2x4 squares at each corner.

Step 5: Lets Add Our Head Mech and Build a Tail.

We now have a standing frame so now we need to add the heads. I just welded the front of the cube just where the necks attach to the underside of the front all thread then again at the rear of the cube to the spine. I also used some thick solid wire to bend around to simulate ribs for the sake of creating a more believable body shape.

Now it's really starting to look like a three headed dog but first we need a tail. The tail on this prop serves an important purpose. It is the pathway for the fog machine piping and the wiring to exit the dog and get to the controller unnoticed. I needed to limit the travel so it wouldn't pull out wires every time it jumped up so I secured a chain from the center rear of the pallet to the end of the spine so that it held the dog just short of the full extension and would have tension from the springs. Next I used some plastic piping I found at Lowes that was a good diameter to fit snug inside the pvc pipes and fittings I was using to split the pipe into three directions to go up and feed into each mouth. Zip ties hold all of this to the chain tail and then along the under side of the spine and each neck. For added effect I also hot glued a couple more LEDs to the sides of each pipe just as it exits at the mouth. Lastly I ran the wiring from all the LEDs and the door lock actuators down the spine and along the chain tail. Then I ran the piping and wiring out the back of the pallet.

Step 6: Put Some Meat on Them Bones.

As you may of noticed in the last step's pictures there was some foam wrapped around the legs. I did this just to add a little thickness to the legs to see if I like the look. I thought it worked well so I went ahead and wrapped the whole body in it. The foam also served as an easier means to attach the fur later. The foam is just wrapped around and then taped around as many times as I needed to keep from having weird clumps.

Step 7: Time for That Winter Coat.

The fur was another compromise as I wanted black fur originally and I had planned to just buy a couple fur coats from a thrift store to save money because the fabric itself is super expensive. (this fur ended up costing me $15 per yard and that was the cheapest I could find) However for the first time ever I couldn't find any fur coats at any of the thrift shops in my area. So in the end I had to settle on this fur (it eventually grew on me and I really like it now). Also just as a heads up for those who don't already know (because I tried and failed miserably then read up on it and learned) those furs can't be dyed so make sure you get a color and style of fur you're gonna be happy with.

After I cut the fur to make a decent fit around the dog (which ended up being multiple pieces to ensure full coverage), I stuck most of the fur to the foam wrapping with velcro so I could remove it in the future should I need to get to the insides for some reason. A couple of the pieces didn't want to stay well and luckily were in less important areas so I just glued them directly using the spray fabric adhesive.

With that all done it was really looking good but I added some small patches of fur to the tops of each head in different sizes and styles to make them unique and put small strips under the lower jaws as well.

It was really coming together and looking good at this point plus it's almost done!

Step 8: Paws.

It's time to add some paws. This was done using some little claw talons that I picked up at Hobby Lobby and I just hot glued them onto the pallet plank just in front of each leg. Then I pulled the fur back and used Great Stuff spray foam to make a basic shape of the paw. Once that dried I carved the foam a little just to clean up the shape some and spray painted it black.

With that all dried up I put the leg fur back on and used the spray adhesive to glue on yet another patch of fur to the tops of each paw.

Now they're a done deal.

Step 9: Hacking the Mini Fog Machine.

Before we can hook everything up to the controller we need to hack the fog machine. To do this I opened up the casing to gain access to the manual switch on top of the machine itself and spliced in two wires to the switch so that when you connect the two wires it will complete the circuit and activate the fog. Then I fed the wires through a couple of the ventilation holes in the casing and reassembled it. I took this time to glue on another pvc fitting to the front nozzle for the plastic piping to fit into as well.

Step 10: The Controller...

So as a controller I chose to try out something really cool that I discovered a little before starting this project. I was looking around the internet for different controller options as the professional controllers you can get from work great but are pretty expensive. I eventually stumbled upon a website that showed a homemade 4 channel controller using an arduino, mp3 module, and a relay board. Being that I just followed the creators instruction in making my own I am just going to post a the website address. In the picture You'll see I used eight channels in all, but the website explains how to daisy chain two arduino's together to make an eight channel controller. Once I finished making this controller (only costed me about $30 in all for the arduino and accessories on ebay, the programing was free from the website, as opposed to the $200 plus for an 8 channel controller from Halloween websites) I just used the included programming software to create my scene complete with ambient and scene audio. Only thing left was to wire up all the pieces to their assigned relays on the boards, plug everything in and it was ready to test out for the first time!

The web address is:

Step 11: The Finished Product.

With all this hard work finally coming to an end I decided to stain the pallet and posts to darken them up which immediately made the whole thing look even better. To help sell the Cerberus feel I used my "lava walls" I had made the previous year, to be our entry way to the party we hosted, as a sort of back drop.

A couple days before Halloween my boss borrowed the prop to use at his local trunk or treat and it won "best Halloween decor" so my daughter decided a shelf for the trophy was needed thus was added a piece of 2x4 to the support boards at the back lol.

What follows are just a few final comments I felt I should add just in case you find them helpful

As a last minute trigger decision I chose to use a little 12v wireless remote relay for a trigger so I could set it off when ever I wanted as people walked through our display.

The over all programming of the scene went something like this: first the dog would be in crouching position held in place by the electromagnet while the ambient sound of fire burning and distant screams are heard. When triggered the eyes light up and you hear growling with a single pre-emptive bark. Moments later the magnet releases and the dog jumps up to standing position as the ferocious barking begins. The mouths open and LEDs around the fog pipe light up with each bark as fog begins to pour out of each mouth. Once it finally gets quiet the actuator pushes the dog down until it engages the electromagnet again and is held in crouching position once again and the ambient sound kicks back on.

The ambient sound I just found online searching for mp3 sound effects. The actual scene sound was a mix I made from several dog sound effects I found online.

The electromagnet was supposed to run on 12v but when I hooked it up it was super weak and wouldn't hold well at all I'm not sure why that is but I tested it on other voltages and found it worked best with a 24v power supply. Do so at your own risk however because I'm sure it's not good on the magnet as it gets pretty hot after a while and I have to occasionally disconnect it to let it cool just to be on the safe side. I'm sure once I've figured out why it doesn't work well on 12v and fix that problem I won't have to worry about it any more.

Also as you may notice from some of the pictures I added a chain that goes from the middle neck to both rear posts. This was done to look like a leash but also because it is crucial for getting the dog to stand all the way up and not just lean forward.

I think that's about it. The last video here shows a walk through of our set up this year some of it's too dark to see just how much is actually going on, should have shot it at dusk but it got super busy fast lol. I didn't fire off the dog in this video because there was a group of kids coming through a little behind me and I didn't want them to walk by right at the end of the scene. I hope you've enjoyed this project it's my take on the Cerberus. I really wanted to out do the Spirit Halloween prop and so far everyone that has seen both are in an agreement that I was successful so I'm really happy with it.

If you have any questions don't hesitate to ask. Thanks!

Halloween Contest 2017

Participated in the
Halloween Contest 2017