Building a Unicorn Costume




About: I am a foam fabricator and own a costume and prop design company called Partybot Designs. I take on commissions of any scale from cosplay costumes to festival stages. Follow me on all social media under "Par...
If you think the costume is magical or creepy...please vote for me in the Halloween Costume Contest:

I start every costume creation by finding an example that is done often, but not to an extreme level. I saw that the only unicorn costumes online were baggy store bought suits or a horn duct taped to someone’s forehead. I knew I could do better and add an X-Factor like fog snorting out the nose.

Step 1: Foam Foundation

Create your foundational foam structure. I recommend using a combination of the dense core home foundation insulation and expanding foam (low expansion and high expansion). Cut the foam by scoring and breaking. Glue it together with Gorilla glue and definitely use clamps. You can insert pieces of wire at this stage to reenforce joints. Don't rush the gluing process and let it cure for a solid day or two.

You can then use your expanding foam to get a bulk structure for rounded areas.

Step 2: Foam Carving

You want to start from coarse carving to fine finish work. The best way by far to cut foam is by using a hot wire tool. You can buy one online, but they are quite expensive. I recommend buying a $5 hair dryer at a thrift store, get the heating coil wire out, and then clamp onto the wire with a battery charger (car trickle charger worked great). You have to work in a well ventilated area without a doubt.

Once you have it roughed out, move to an electric carving knife which you can find at a thrift store also for about $10.

Then comes the dremel for the concave portions.

Finally I get the details done with a mesh drywall sander and dry wall spackle.

I also attached a photo showing a foam lego head I made last year to show the rough carving.

Step 3: Upholstering

Buy elmers spray adhesive and carefully stretch the fabric over the shape in sections allowing it to dry inbetween areas. Think ahead to where seams will have to be made. For high stress areas you can dip a staple in gorilla glue and press it through the fabric and into the foam.

Step 4: Amazon Shopping and Lighting

This is a shameless plug, but you should get an Amazon Prime account if you want to do things like this. I had to order the fur cuffs, fanny pack, 7 wigs, fiber optic lights, and shipping adds up.

You can see from the video that I mounted LEDs and fiber optic lights all through the mane and in the horn to give the magical rainbow effect. If you do the fiber optic hair extensions, you'll want to cut it into multiple layered lengths or you'll just have a hard line of color at the end.

Step 5: Fog, Confetti, and Spandex

I wanted to add the X-factor of snorting fog.

I took a typical can of compressed air. Remove the top trigger portion. Fill the hole where the air typically comes out with hot glue (don't use too much or you'll clog the whole thing). Drill a hole through the side into the path of the air. Insert your the tiny hose tube that comes with the can, hot glue and silicone into place.

You can then take a threaded rod and screw it into the tip that you filled with hot glue as a trigger extension.

I mounted the can of air in the head using a plumbing mount, screws, and gorilla glue.

IMPORTANT: The can must be mounted upside down or at an incline so the liquid gas is shot out.

CAREFUL: If liquid leaks out of the can it will burn any skin it touches. YOU'VE BEEN WARNED!!!

For the body of the costume, I originally got a morph suit and airbrushed on details. After some demo runs I bought some spandex pants to double layer. No one wants a "blow out" when you're dancing your unicorn butt off in front of 1000 people.

Halloween Epic Costumes Contest

Finalist in the
Halloween Epic Costumes Contest

Make It Glow

Participated in the
Make It Glow



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    19 Discussions


    3 years ago on Introduction

    Hey! I love your costume, but I REALLY love the effect of the compressed air. I am trying to make an Avatar the last airbender Zuko, and was hoping I could use a similar effect to make it appear like I am shooting fire out of my hands, but I'm a little apprehensive about possibly burning my skin off, as I would have the nozzle likely near my or on my person.... Any ideas as to what I should do?


    at least you knew what was talking about I came back and I read my comment and im like what was I thinking it sounded like I was a little kid


    4 years ago

    Great job, I wanted to make a horse.... I guess this will work fine.


    5 years ago

    Wow...what a large...horn you have there


    Reply 5 years ago on Introduction

    I can see out the mouth and then the entire bottom of the lower jaw is wide open so it was super easy to see where I was going. The main annoyance was the weight. If I were to do it again, I would build a light metal armature using plumbing strapping, a bike helmet, metal wire that can be hot glued into shape, paper mache, and then upholster. It would cut weight by about 75%.

    I'll be posting the techniques in a couple days when I add this year's Dragon costume.


    6 years ago on Introduction

    Congratulations on being a finalist in the Halloween contest!!! Can’t wait to see if you win! Good luck!

    2 replies

    6 years ago on Introduction

    This is fantastic!!!! Very well done 5 stars and a vote for you!


    6 years ago on Introduction

    I love unicorns...

    but I'm gonna have to file this one under creepy.