Introduction: Happy Mutant 3-Armed Baby Costume

Picture of Happy Mutant 3-Armed Baby Costume

This year we were a Nuclear Family for Halloween, with our 4-month-old daughter Corvidae dressed up as a 3-armed happy mutant.

While we wanted to be subtle, this was almost too subtle - she wore the costume all day, and hardly anyone noticed!  But when they finally detected a problem, the responses were excellent.

This instructable documents the creation and care of a 3-armed baby.  If you make your own, please post pictures!

Step 1: Find Radiation Sources

Picture of Find Radiation Sources

As with many superheroes, Corvidae's mutation is the result of irradiation.  in this case, both of her parents take serious rads on a regular basis - Eric as a Beam Engineer at North Central Positronics*, and I as head of the Experimental Radiology department at Mid-World University*.

radiation-induced mutant powers are highly idiosyncratic.  We cannot guarantee your child will be born with super strength or telekinesis, or that any extra limbs will be fully functional and/or not evil.

Since we had to leave our real badges at work (pesky government regulations!) Eric quickly cut duplicates on the Epilog laser cutter.

*Hat tip to Stephen King's Dark Tower.

Step 2: Find Duplicate Outfits

Picture of Find Duplicate Outfits

To clothe your adorable 3-armed mutant, you'll need duplicate outfits, as few baby clothes are sold with an extra sleeve.  Choose highly-patterned clothing for best results.

Step 3: Find Suitably-sized Doll

Picture of Find Suitably-sized Doll

A similarly-sized doll can be useful in sizing the costume for your 3-armed baby.  We'll use one of its arms to mock up the outfit, though of course we'll substitute Corvidae's real third arm when she wears the outfit.

This doll has realistic plastic hands, and a cloth body - perfect for our purposes.  Choose the hand with the most realistic positioning.

Step 4: Prepare Doll Arm

Picture of Prepare Doll Arm

Cut the doll's arm off at the shoulder, leaving as much extra material as possible.  Test against the sleeve of your outfit - the arm should be long enough to fit comfortably, just like your baby's real third arm.

Stuff a bit more cotton in the upper arm/shoulder region, then hand or machine stitch the openings shut. 

Dispose of doll carcass, saving any useful bits for future projects.

Step 5: Prepare Third Sleeve

Picture of Prepare Third Sleeve

Cut the sleeve from your sacrificial outfit, again leaving extra material arund the shoulder region to accommodate future sewing.

Test your doll arm inside the sleeve - is it long enough, and properly plump?  Did you use the appropriate matching-side sleeve?

Step 6: Sew in Third Sleeve

Picture of Sew in Third Sleeve

Use a seam ripper to open the seam directly below the existing arm hole in your final outfit, extending the hole just far enough to fit your third sleeve inside.  Adjust the new sleeve position so it matches the original sleeves, then turn the outfit inside-out to pin the sleeve in place, right-sides together.

Sew sleeve in place, stitching right inside the edge of the split seam.  (you'll likely have extra bits of cut sleeve protruding beyond, which is fine.)

Turn the outfit right-side out to admire/check your work.

Now you can sew your third arm into the sleeve, anchoring it at the shoulder only for extra-lifelike flop.  Alternatively, go put the suit on your 3-armed baby.

Step 7: Dress Your Happy Mutant

Picture of Dress Your Happy Mutant

Of course she's happy - she finally has a custom pantsuit, specially fitted to accommodate her third arm!  Be careful, though - with three arms vs. your two, you may need help getting the pantsuit on.

Step 8: Put Her in the Carseat

Picture of Put Her in the Carseat

With five flailing limbs, this may prove difficult! 
Be sure to secure all three arms underneath the shoulder straps.

Step 9: Visit the Farmers' Market

Picture of Visit the Farmers' Market

Take you happy mutant out on the town!

Most people were completely oblivious.  When people smiled at Corvidae, I waved her third arm back at them - everyone smiled again and returned the wave, clearly not bothering to count arms.  Only those who had several minutes to examine her up close while I paid for groceries ever noticed something was amiss. You could tell when they saw it - their eyes were suddenly huge, surprised and amused/horrified all at once. Even after we told people she was wearing her Halloween costume, it often took a while for them to catch on.

My favorite anecdote: a lady came up to us at the market, and asked if she could say hello to the baby.  We watched with amusement as she spoke to Corvidae, put her finger up for the baby to grab - and offered it to the third hand.  She seemed a bit disappointed when the baby didn't grab her finger, and stepped back.   Finally her eyes widened in shock.  "Your baby has three hands!"

Step 10: Pose for Family Pictures!

Picture of Pose for Family Pictures!

Document your nuclear family!


sheraphoenix made it! (author)2011-10-26

We loved this idea and made our daughter a 3 armed baby for Haloween 2011. It's a big hit! Thanks for the idea.

canida (author)sheraphoenix2011-10-27

She's so cute with her vestigial limb. Thanks for sharing the picture. :D

nemalim (author)2013-11-03

Amazing! Too bad I saw just now, three days after Halloween. My baby would have such a great mutant! I wander if you could be a mutant on Purim?

zapper067 (author)2011-08-12

th hands are too small so it looked like a fake.Only if it is bigger

canida (author)zapper0672011-10-27

Vestigial limbs are often smaller!

SgtJellyfish (author)2011-10-12

this is now my team fortress 2 spray :D love the pic!

wizcling68 (author)2011-06-26

I liked the fact that nobody realy picked up on it. That's what I call a costume. Cute kid

RavingMadStudios (author)2010-11-03

This is fantastically, beautifully, wonderfully subtle. I love it!

It doesn't hurt that the baby is just a little bit cute.

aalison (author)2010-11-01

That's gorgeous.
Perhaps next year you could do a beeblebaby.

brightside.janet (author)2010-10-29

Hi Canida, this is such a clever idea and her smile is utterly adorable! I just had to include it in "10 Halloween costumes sure to get a smile" ( I've emailed you about this and hope you don't mind us linking to you. Janet

platypusymphony (author)2010-09-30

That is an awesome costume - what a great idea! Also, your baby is incredibly adorable and lucky to have such creative parents.

ocampolm (author)2010-09-29

Genius! I love the family photos

rusty0101 (author)2010-09-27

No mutant babies were harmed in the construction of this Halloween costume. Can't say the same about dolls, but at least this "Chucky" won't be doing anything left handed... :-)

Great job by the way.

TRANSLTR (author)2010-09-26

Brilliant - I have to make an adult version as my kids are too old!

janettetsmith (author)2010-09-26

Buwhaha! This is great.

jwjohnsen (author)2010-09-26

Love the cloth diaper.

Jon B3 (author)2010-09-26


The rest of Australia reckon us Tasmanians have got two heads... this would show them!

linny (author)2010-09-26

Excellent!!! When he gets older, this child will probably fully appreciate the humor behind this wonderful gag. This is one of the funniest things I've ever seen-- Hope you'll keep evolving. I love humor.

mman1506 (author)2010-09-26

for people in toronto go to active surplus there known for there baby parts

KWHCoaster (author)mman15062010-09-26

The limbs have moved from a shelf to a bucket at the back. :-)

The bucket of arms must give a few people a start as they walk by.

Strombergundy (author)2010-09-26


baba87 (author)2010-09-03

Im so gonna do this with my kids someday

jongscx (author)baba872010-09-26

make a costume or expose them to radiation to grow extra limbs?

aramanthe (author)2010-09-22

I lol'd hardcore at the badges. The reverse of my (real) work badge says "North Central Positronics, Alyce O'Dim"

hammer9876 (author)2010-09-14

For the first time in my life I want a baby! Can I borrow someones?

canida (author)hammer98762010-09-16

As far as I'm concerned, awesome Halloween costumes the #1 reason for having kids!

Well, awesome Halloween costumes that are recorded on the Internets for blackmail purposes in adolescence. ;D

starrydynamo (author)2010-05-24

 Hands down the greatest baby costume I have ever seen!

ekobor (author)2010-02-26

 Very cute.

HelloChild... (author)2009-11-04

 You're a monster!

↑↑↑↑↑ ↑is right and thats sad

rbbiggs (author)2010-02-11

Penn State college of Medicine?  hahahahaha!  You guys are a crack up !

rbbiggs (author)2010-02-11

This is just too funny.  I wish I had seen this idea a few years ago when my kids were this age !!

Chapu (author)2010-02-03

HAHAHAhaha this was great!!! 
I´m gonna make one for my first grandchild :-)

kelseymh (author)2009-11-04


canida (author)kelseymh2010-01-14

;)  We try.

Tunesrlife (author)2009-12-28

Just a suggestion for IF you wanted the other arm to move on it's own-
You could connect it to the upper one in a couple places with a bit of fishing twine. 
Awesome by the way :)

anonymouse197 (author)Tunesrlife2009-12-31

 would fishing twine not be a bit thin and possibly lethal?

Tunesrlife (author)anonymouse1972009-12-31

What do you mean lethal!?
Maybe I didn't explain it very well.  I suggested that someone could tie a bit (maybe an inch or two) or clear plastic string from lower arm's sleeve to the upper arm's sleeve so that when the real arm moves, the other will follow, because it's attached to the real one.  Thought it could be kind of cool, instead of just having the fake arm hang there.
...I dont really understand how that could be precieved as lethal.  If I am incorrect, please explain it to me.

anonymouse197 (author)Tunesrlife2010-01-01

 Sorry - I misinterpreted your comment. I thought you meant tying fishing twine round the REAL arm and thread that through the clothes to the fake arm, possibly cutting off the blood flow. Sorry. Silly Me! :P

filigree (author)2009-11-22

 I see l'm a little late, but this is a great costume! I love that it's so subtle and kinda disturbing. It's fun to play with people's heads, even if you ended up doing it inadvertently!  I had a similar Halloween: When I was in 5th grade I dressed up in street clothes with a ground-off six-penny nail glued to my forehead in a bit of bloody wax scar material. Far more people invited me into their houses for first aid than offered me treats! It was a really strange and fun experience (that led me to become a makeup artist for a while!) Good job! 

My son is now old enough that all he wants are commercially popular costumes - but at least I get to make them. Enjoy this time!

erosser (author)2009-11-13


sarahfish (author)2009-11-09

 totally inspired by infant halloween costumes this year!
Also saw an infant dressed as a lobster, and her parents wheeled her around inside a big stock pot all night! Just brilliant!  More people should have this much fun with their kids!

anteejean (author)2009-11-06

best looking 3 armed mutant baby i ever did see!

domestic_engineer (author)2009-11-05

Love it! Definatly a pic for the baby book.
I would love to see it as a x-mas card, just sitting next to the tree in an x-mas outfit, with 3 arms. I wonder how many relatives would notice.

CameronSS (author)2009-11-05

I love the "scheming" shot...that child is definitely going to take over the world one day. This is definitely looking like Spider-Man villainy...first the pumpkin bombs, now the robot arms. Be afraid.

Forkable (author)2009-11-05

Ahhahahah!  Lovin it!

orksecurity (author)2009-11-05

Nicely done. Good job finding a hand that was more-or-less scale appropriate.  And the badges (especially the dosimeter) are a wonderful supporting touch. (For those who don't have a laser cutter: A small router or rotary engraver, and a pantograph, will do the job.)

Inflicting it on the general public may have been just a trifle cruel (to them, not to the kid)... though the temptation must have been irresistible.

jeff-o (author)2009-11-05

Sheer brilliance, that's what this is.

Rob K (author)2009-11-04

Everything is better in Mid-World. How are the cyborgs coming along?

Nice baby costume.

caitlinsdad (author)2009-11-04

 Actually knowing some kids with birth defects and malformities, this is kinda scary from a parent point of view.  But it would totally work on an adult costume.

About This Instructable




Bio: I've been posting Instructables since the site's inception, and now build other things at Autodesk. Follow me for food and more!
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