Alien Xenomorph Kids Costume (long Version)




Introduction: Alien Xenomorph Kids Costume (long Version)

So, my 10 year old wanted to be the Xenomorph for Halloween. Previously he's been the alien from Attack The Block and Nightmare from FNAF. Every year we learn a lot so I'm sharing our successes and mistakes on this most recent project. I need to give lots of credit to as he has made an adult version of this that provided much guidance and instruction. Also other Indestructable posters who have also made Xenomorph costumes.

Anyway, we started with the head (of course) which was carved from insulation foam (the 2" kind with the pink panther on it from Lowes). I measured the boy's head at 8" diameter so went with a 10" width on the head. Lot's of glue. I used Foam glue but liquid nails might also work.

Anyway, I projected an image off the internet to trace out the head (the Giger one with helmet) and then did lots and lots of carving and sanding. Lots. This part is hella messy so don't try it in your dining room (ask me how I know). I did it in two halves to have access for interior carving.

I used pretty rough guage sandpaper at first then moved to really fine as things started shaping up

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Head

Step 2: Head

Like I said, the head is important so carving and sanding matter

Step 3: Head 2

Step 4: Head

Step 5: You Know

Step 6:

Step 7: Jaw

Step 8: Jaw

Step 9: Jaw and Head

So, after extensive spakling (and more sanding) I coated the head in Epoxy Resin and made the jaw out of that kind of foam matting that the ABC mats or interlocking mats in a yoga studio are made of. It's good to have a heat gun cause that makes it easier to shape things. I carved the jaw with an xacto knife. Teeth are made from Instamorph (as a note, they are too large here as this was still testing and fitting. Another important thing is that the extruded polystyrene (EXP) I used will dissolve if you use incompatible products like polyurethane or regular spray paint. More on this later. I also carved out the inside of the head for my kid's head to rest in. Lots of lightweight foam makes it comfortable. I mean really soft stuff like you can get at Michael's which is also really thin. I found that the Design Masters spray paint (available lots of places) is "foam safe" so I chose to use that in Satin Black. There is a lot of discussion about what paints work with XPS and it's actually the accelarant in the spray that eats foam so you might get away with less expensive paint if you spray from a distance. I was super nervous so, in addition to the epoxy resin, I brush painted with black acrylic paint before I put anything else on. Obviously, test everything because people lie about their products.

Step 10: All the Stuff

The details on the head are actually commercially available things like electrical wire wrapping (split type), suction pumps, etc. I cut these up and used hot glue to attach them to the head. I have bad hot glue technique so switched to using instant adhesive (super glue) with a brush which sort of worked better but also you will go through hella brushes. I used really cheap ones that cost, like, $10 for 50. I'm honestly not sure what the best way to do a lot of this is as super glue doesn't work on everything (foam, morph suits, yoga mats, etc) and will eat up XPS if it's unprotected. Hot glue is great but messy. It's a toss up for me. Opinions welcome.

The chin strap is attached to the head with elastic (using velcro) and then there is a wire running to the jaw so that it will open when the wearer opens their mouth. As always, I had issues with the velcro failing over time so will move to plastic clips when I make some upgrades. The wire needs to be attached on both sides of the jaw and is the reason that the top of the jaw is so wide so that you get maximum mouth opening with minimal mouth movement. This turns out to be particularly important with a child as their mouths are small. Fortunately, my kid is fond of yelling so has better jaw extension than a milder child might have.

Step 11: Lip

Step 12: More Lip

The Xenomorph has a distinctive sneer that I did my best to replicate. I attached high test fishing line to the jaw, drilled a small hole in the snout, bent up some coat hanger wire, and covered it in a bit of black trash bag so that when the mouth opens the lip comes up. It's more subtle than I wanted but this is where I had to start reminding myself that this is a costume for a 10 year old and it doesn't have to be perfect. I told myself that a lot to little result but seriously, it doesn't have to be perfect....or does it?

Step 13: Ribs

Step 14:

Step 15:

Step 16: Ribs Plus Back

For the ribs I used the same floor mats (the 1/2" kind that interlock like the ABC mats your kid might have had as a todler) and just carved and cut. This is where a high quality action figure comes in handy. I found this part way easier with the kid size tailoring manequin as there are some weird angles that might not be immediately obvious. I used thinner 1/4" (approx) foam mats for the shoulders and shoulder wings. I covered it all in different diameters or plastic piping/ wire covering like you can find at any hardware store. I used a dremel with the pointy sander tip to shape the ribs.

The back is a teenage mutant ninja turtle shell my kid had lying around.(lay? Lie?) and I made the tubes out of the same thinner foam (1/4") and plastic tubing. I didn't get the exact shape I wanted and, as I'd used hot glue, I couldn't really reshape with the heat gun so maybe super glue is better for this but I had hella trouble getting it to adnere to the foam so just went with what I knew. This is where the "doesn't have to be perfect" mantra really kicks in (and gets ignored)

Since the shell was hard plastic, I drilled holes and used oversize washers and bolts for more stability. There's probably better ways but this worked and )still) seems solid.

Too, as you will see later, the back had to be slightly oversized so cover the compressed air tank and solenoid for the inner jaw mechanism. See what I did there? That's foreshadowing (I think).

Step 17: Coming Together...

As with any costume it's important to keep testing how things work together. With a complicated costume I suggest testing until the child is weeping and angry as this is the only way to know whether they will be able to wear the costume for more than 15 minutes. I don't know, maybe there is another way. My kid is actually super stoked on costume testing so would sleep in it if I let him. I will say I made some mistakes with the Attack The Block costume that only came to light after an hour of trick or treating (it was too hot, I used the wrong kind of foam that didn't breathe, also super heavy)

Step 18: Way Too Hot Costume

some foame breathe, some do not. Do your research

Step 19: Tail

Step 20:

Step 21:

Step 22:

Step 23: Butt!

Step 24: More Tail

So, the tail is super important. I had issues with mine because I initially used to weak a rod to shape it and it wouldn't stand up. I used the flag mounting thing (another person on here gave me the idea with their xenomorph costume which is awesome) and made a little tail extension to cover it so it looked like part of the costume. I made a butt plate out of the same 1/2" matts then gued in a little strip of metal (very thin) which I mounted the flag holder to. This is mostly for ease of travel. I wanted the costume to be comfortable but also easily dissassembled for car rides, etc. The tail mount assembly was attached to a belt that went on before anything else and there was a little hole in the back of the morph suit where everything got attached once the body was on.

If I had it to do again, I'd use a flat piece of aluminum to give the tail flexibility and rigidity. Actually, I did have it to do again since I started early on this costume so that's what I did and it worked great once I clamped it to some pvc pipe that I had already installed in the tail to plug into the flag holder.

Step 25: Body!

Step 26: Body!

This part took forever (not as long as the head but, you know) cause it's a ton (metric) of glueing. I could not make super glue work and it would bleed through the morph suit and stick everything together so I went with hot glue which is ok but will give way when stretched which you have to do to get the suit on. Again, advice welcome here but it ended up working fine aside from the need for occasional touch ups. I initially wanted to sew the patches into the costume then cut away the morph fabric for a 3D effect but my first effort at that revealed that it was beyond my skill set so I opted for attaching them to the outside.

Actually, after this picture, I was displeased with the unevenness and redid it all cause mantras are for suckers.

Also, there is a little cod piece at the groin that covers the slit I made in the suit for the wee-wee cause I am not taking all this off every time this kid gotta pee. It will be visible in later pictures (the cod piece, that is)

Step 27: Neck

You really can't go too far at this point. I made a rough pattern and just sewed the fabric with a little fluffy foam in the middle then decorated. Then glued it into the head

Step 28: Hands!

I'll be honest, I ordered these from a latex manucacturer. My kid wanted original alien hands and these were like $30 and saved me tons of time except for cutting all the latex edges and painting.

Step 29: Feet!

These are just old sneakers with some decoration. I made claws out of instamorph, painted them silver, and attached them but I didn't get a picture of it because I didn't like the claw placement and by the time I got it right it was, like, 4am and my wife was pissed. I mean, she's generally very understanding about this stuff but I suppose everyone has a limit

Step 30: Pnuematics

This picture is confusing, I know. What you see is a 9oz C02 tank mounted in the back of the ribs, a solenoid to activate a two way pnuematic cylinder, and a battery pack to power the control button that is in the kids hand. That's why I needed the TMNT shell to give it all some space. The pnuematics were hit and miss though this is largely my fault as the 9oz tanks don't last long and, though I had 6 of them, Dicks sports could only refill 2 on the critical day of Halloween. Anyway, I'm still making some adjustments but it works well overall.

as a note, the pnuematics add some weight so I reenforced the thinner foam on the shoulders with old seatbelts from my '66 VW beetle and I put a strap from the back (where the heavy stuff is) to the head for extra support. It worked ok but I used velcro which gives out over time so I'm switching to 1" plastic clips (on elastic) for future upgrades.

I got all the pnuematic stuff from Fright Props who were great about delivery and have all sorts on online tutorials. I chose the pnuematic tube as it gave the very satisfying fast action that I want in my Xenomorph. Other solutions may be more practiacal but this worked for us. If anything, I went too big in getting an unneccesarily long tube (8" extension) where 4" or 5" would have worked just as well though mounting them would present another set of (totally surmountable) problems

Step 31: Finished Project and Progress Videos

Step 32: Finished Project and Progress Videos

Step 33: Finished Project and Progress Videos

Step 34: Inner Jaw Experiments

For the inner jaw I used some more ribbed plastic tube and made the teeth our of instamorph

Step 35: Early Tests

Step 36: Final Testing

Step 37: Final Testing

So, that's it for now. Thanks for reading. I'm continuing to make some changes for the 'cons we might go to so feel free to contact me if you want more detail about anything. My kid had (and hopefully will continue to have cause...lot's of work, duh) a lot of fun with this costume.

Halloween Contest 2017

Participated in the
Halloween Contest 2017

Be the First to Share


    • Cardboard Speed Challenge

      Cardboard Speed Challenge
    • Sculpting Challenge

      Sculpting Challenge
    • Heart Contest

      Heart Contest

    8 Discussions


    5 months ago

    Can we buy this from you?


    Tip 1 year ago

    for the body detailing try to cut thin strips of the pool noodles and then sewing them in place.

    DIY Hacks and How Tos

    That is so awesome! I love how you were able to make it out of foam instead of molded plastic. Your method is something that I could actually do.


    Reply 2 years ago

    Thanks! I can't take credit though, I saw that other people had used foam. I used Foamular 250 (2") cause that was what was easily available locally (Lowe's). I found that it was really easy to work with.


    2 years ago

    Wow, you should really change the title picture. It doesn't do the final product justice at all!


    Reply 2 years ago

    Thanks for the tip! I took your advice


    Reply 2 years ago

    Ha! I wish it was as easy as one costume a year