Introduction: Tentacled Four Armed, Four Eyed Alien Costume.

About: I work on a rotation which gives me plenty of time at home to build stuff for fun for myself or as gifts. I have been making stuff since I was a small kid and I have always enjoyed being creative. I'm between …

For Halloween my son asked me to make him an alien costume and I was quite excited to give it a go because I could really let my imagination go wild. I wanted to come up with something a bit more alien than the usual Humanoid "Grey" or Star wars themed alien so I had the idea for a 4 armed tentacled beast that I think did the trick. At the same time I didn't want to make anything too scary because my son and his friends were only 9.

The build took about 4 hours a day for 3-4 days but mostly because I was trying out new materials and new techniques but I learnd a lot and once I had worked out what I needed to do it was fairly easy.

The costume like many of my projects evolved as I went along and what was initially supposed to be a simple alien morphed into the beast you see in the picture.

The costume consists of 4 main parts;

1) A bulbous head with tentacles, 4 eyes and tentacles around the mouth.

2) The Body, with 4 arms.

3) 4 pairs of claw like hands with 3 fingers each.

4) 3 toed clawed feet.

Step 1: Materials and Tools

What you will need to make this costume;

2 - 3 400 ml (13 ounce) cans of quick drying expanding Polyurothane "PU" foam. For the head and the feet. (€8 per can)

2 x 1m (3 foot) lengths of foam pipe lagging for 1" pipes. for making the other 2 arms (€2 per piece)

2 pairs of rubber coated garden gloves for making the alien hands (€2.99 per pair)

At least 10 foam 5-10mm (1/4" - 1/2") thick bathroom / kitchen cleaning sponges (99cents for a pack of 10)

A piece of 3 mm (1/8mm) thick upholstery foam, approx 30 cm / 1 foot square wide and 2m (3 foot) long. (I can't remember how much this cost but I am sure it was not more than €5.)

2 pairs of "alien eyes" novelty Sunglasses. (These cost me €1.99 a pair from a bargain shop) but you can still get them on ebay for less that $5

A pair of old "crocs" (Foam garden shoes) that fit the feet of the person who will wear the costume. (€3 from the same bargain store)

2 cheap thin green long sleeved t-shirts. (Less than €2 each from a kids clothes store)

Green and yellow coloured bathroom silicone sealant and a application gun to apply it. (This was less than €10 a tube and I only used about half of each tube)

The rest I already had;

A large latex party balloon.

Quick drying PVA wood glue.

Acrylic paint.

A hot glue gun and white or clear hot glue sticks.

Duct tape.

A piece of hard foam interior insulation. (this I used to make the moulds for the tentacles)

A small and a large retractable craft knife.


Paint brushes

Sewing needle and green thread.

A piece of dressmaking elastic about 1m long

Rotary carving tool with assorted bits. (Such as a dremel)

wood working files, rasps, Stanley "Surform" or similar.

Assorted sand paper.

Step 2: Making the Head.

2.1) Initial attempt. Once I had an idea of the sort of head I wanted to make, I initially tried to make the head out of Papier mache and then build on that. I used a party balloon and then covered it in newspaper stick on with diluted wood glue. After putting on about 6 layers of Paper and letting it dry I popped the balloon and removed it. It was obvious immediately that the papier mache was too thin and fragile to make a suitable alien head. I sprayed a layer of PU foam into the papier mache but I think I overdid it because it completely filled the cavity and spilled over the top of the opening. I waited for this to dry and then cut it open and removed the over spill section. I don't know if I failed to mix the foam properly but Inside I found a lot of liquid PU so I abandoned the head. However this was not a complete failure because the piece I had cut off ended up being the face of my alien.

2.2) Attempt 2 - Alien brain head. I blew up another balloon making sure it was quite a bit bigger than my sons head, I then taped it down onto a piece of cardboard and mixed one of the cans of PU foam. I then slowly sprayed it onto the balloon making sure it covered the whole balloon. The expanding foam covered the balloon well and it soon dried into a pattern that looked very brain like. Excellent! one side of the "Head" was very thin so I cut it out and replaced it with the face piece I had salvaged from my earlier attempt. In order to connect the 2 pieces I attached it in place with a 10 cm (4") strip of thin 3mm thick upholstery foam inside using hot glue. This also gave the face some flexibility and allowed it to move. I coated the foam join in a layer of slightly diluted PVA wood glue mixed with green & blue acrylic paint. This gave it a smooth surface.

I then made a neck piece out of the remaining 3mm upholstery foam, cutting it so it flared out at the bottom so it would lie flat on the shoulders. I then attached this "Gorget" piece to the head with hot glue and I then coated it in a the same mixture of green / blue acrylic paint and PVA wood glue. Once dry the glue / paint mixture was still fairly flexible, with a smooth surface, but the downside was that made the foam a little bit fragile and quite easy to tear. (In future I would use a more flexible base and I have just seen that there is an Instructable by author stuartbray detailing how to paint foam and how to make durable flexible paint out of Pros Aide adhesive and Liquitex acrylic paint.)

I then mixed a suitable alien dark green colour mixed with a bit of PVA glue and painted the whole head. I mixed a bit of a lighter colour and drybrushed the head to pick out the raised features of the brain like head.

2.3) Creating the tentacles

Having done a fair bit of DIY in my time I have had plenty of opportunity to use silicone bathroom sealant and once dry it is incredibly tough. I found coloured sealant in my local hardware centre by accident and I decided to have a go at making silicone tentacles for my alien beast. I bought green and yellow silicone sealant. The green sealant was close to the colour I ended up painting the head which is one of the reasons I close that colour.

To make the molds for the tentacles I used a couple of pieces of left over rigid polystyrene (Styrofoam) interior insulation where I traced out the tentacle shape with a felt pen. I then used my Dremel with a bullet tip grinding bit to carve out the tentacles. I added bumps on the surface and these I filled first with yellow silicone before filling the rest of the mold with green silicone. I used a flat scraper to smooth off the silicone and leave a flat side. As a final touch I used a pen cap to make shaped imprints in the flat side and I then left the tentacles to cure completely. When the silicone was cured I found that removing them from the moulds was very easy and they came out really well and all I had to do was trim the excess with a pair of scissors and they were good to go.

2.4) Making the eyes and mouth.

2.41) The eyes were made out of the lenses from 2 pairs of novelty "Alien Eye" sun glasses that I found in a cheap discount store. Initially I intended to cut the glasses and embed the frames in the face but I found that it was very easy to simply pop the lenses out of the frame. I placed the lenses on the face where I wanted them to be and marked around then with pencil. I made sure the lenses were at human eye height so that my son had good vision and I then cut out the eye holes slightly smaller than the lenses, trimmed off a piece on the front so the lenses could be "set" into the face and glued them into place with hot glue.

2.42) For the mouth I drew what was basically an oval shape surrounded with teeth and I cut this out of the foam with the small craft knife. I then carved the teeth and shaped them with my Dremel. I then painted the mouth and teeth red with "the blood of his victims".

Finally I attached the tentacles around the mouth by cutting small slots surrounding the mouth and then gluing them into place with more clear hot glue.

2.5) Finishing.

Finishing the head involved painting around the tentacles and eyes to cover up the glue and adding a bit more paint texture to the bulbous head. I had considered adding some pulsating purple & blue veins to the head but I decided against it because it already looked pretty good, it was getting close to Halloween and I needed to get the costume finished.

Step 3: Making the Hands and Arms

3.1) Making the hands

In order to make 2 identical pars of hands I used 2 pairs of rubber coated garden gloves. These were already coated in a dark green rubber coating which was pretty close to the correct green. This alien only has 3 fingers so I needed to stick the little finger / ring finger together and the index and middle fingers together. I tried cutting bits of foam for this to fill in the gaps between the fingers but this didn't work so in the end I put the glove on my left hand and simply stuck the fingers together with hot glue.

You need to be careful with this because the glue is very hot and the glove fabric is right next to your skin, but I kept a cup of cold water beside me and I kept wetting my right hand in water and then smoothing the glue with my fingers. It will still be pretty hot but it will not burn you if you wet it and also still malleable if you wet it immediately after application. I have pretty heat resistant fingers but if you want to completely negate the possibility of getting burned you could stuff the gloves with news paper which can be removed later.

Any bumps you don't want can be cut off with a craft knife or can be smoothed out with an electric soldering iron or in my case I used an electric hot air blowgun to warm up the glue and allow it to be shaped when it got too hard.

It took some time but after a while I had built up the finger shape till I had the clawed 3 finger graspers that I wanted. I then painted the entire glove the same green colour as the head.

I then repeated the whole procedure with the right hand glove that I simply put backwards on my left hand which allowed me to shape it with my right.

3.2) Making the second pair of hands

In order to make the second pair of hands the first thing I did was fill both gloves with left over expanding PU foam. This expanded quickly and filled the gloves nicely. It also allowed the "Hands" to be shaped before the PU foam had completely cured.

I then glued the fingers together, put the hands aside and prepared to make the extra arms.

3.3) Making the arms

For the arms I used the 2 sections of pipe lagging that I had bought from the plumbing section of my hardware store. I measured the length of my sons forearms and upper arms to make sure the alien arms were roughly the same length. I then cut 4 pieces the same length. I joined the upper arm section and forearm section with a doubled up piece of 3mm foam which I fixed in place with duct tape.

To give the arms some shape I cut some "muscles" out of the foam kitchen sponges and glued them in place with hot glue.

I then glued the hands in place with hot glue. Finally I covered both arms in a 3mm layer of the foam and stuck it in place with some dabs of hot glue. Finally I used some Duct tape to make it a bit more robust. I made sure that there was an extra 20cm of the 3mm foam at the shoulder which I would use to attach the arms to the body of the costume.

3.4) Finishing the hands

I then used hot glue to fill in the gaps between the glove fingers and form the clawed 3 fingered alien hands as before and finished them off with the same green paint.

Step 4: Making the Alien Feet

4.1) Making the alien feet

Making the alien feet was actually very easy and to do it I bought a very cheap pair of Crocs, or in this case knock off Crocs from a bargain shop. I made the feet one at a time. I used a couple of dabs of hot glue to stick the Croc temporarily down onto a piece of cardboard and then I drew out a rough shape of 3 toes.

I then mixed a can of my new favorite craft material, quick curing "PU expanding foam" and I covered the Croc making sure to create 3 rough toe shapes with the foam. I let it cure for an hour or so until it was hard.

4.2 Carving the alien foot shape

I then removed the cardboard from the Croc and used the craft knife to carve the foot into roughly the final shape. Fine detailing was done mainly with my Dremel and the same bullet tipped grinding bit until I was satisfied. I also used the craft knife as well for fine detailing. The hard PU foam is easy and quick to carve and shape and the first foot only took about 30 minutes to complete once I started carving.

I then repeated the process for the second foot and once complete, I sanded both feet down with fine grain sand paper and painted it with a couple of coats of the same green acrylic paint. As with the head I used a lighter shade of green to drybrush the raised parts of the feet and left them to dry.

Step 5: Making the Body

5.1) Creating the body.

This was the easiest part of the costume because I just used 2 green long sleeve T-shirts that I bought from H&M for €1.99 each. They had a large skater motif on the front, but that didn't matter because I planned to cover the front and chest anyway.

5.2) Making the chest pieces.

The chest pieces were cut out of foam kitchen / bathroom cleaning sponges which was stuck onto the front of the T-shirt with hot glue. Make sure you put a piece of cardboard inside the T-shirt before you stick on the pieces or the glue will seep through and stick the front and back of the shirt together. Once the pieces were stuck down Painted them with the same paint. This effectively covered up the motif.

5.3) Attaching the 2nd pair of arms.

I took the arms and folded the excess foam in on itself and then stitched the arms onto the T-shirt under the real arms. I then took the second T-shirt and carefully cut the shoulder stitching on the sleeves with a pair of nail scissors so as to remove them without damaging them. I then pulled the sleeves over the spare alien arms and stiched them into place. I also carefully glued the cuffs down on the wrists. so they didn't flap.

The last thing I did to the arms was attach a piece of dressmaking elastic to each wrist on the spare arms and on the other end I made a loop which was passed up and slipped over my sons wrists which allowed the second pair of arms to move in unison with his other arms. I actually cut a small hole in the upper arms to allow the elastic to go though and not wrinkle the upper sleeves.

Step 6: Putting the Costume Together & Final Thoughts on the Project

6.1) Putting the costume together

Putting the costume together was simply a matter of putting on the body like a sweater and attaching the elastic strips to both arms. We decided on a pair of purple jogging tracksuit bottoms which we already had and then it was a matter of putting on the hands, feet and head and the costume was complete.

6.2) Final thoughts on the project.

The initial plan to use papier mache and then fill it with PU foam was a mistake for a couple of reasons. The Papier Mache was too flimsy to make a decent alien head without spending a lot more time on it.

PU foam needs to be mixed properly otherwise it does not cure and for making props or costumes it's worth paying more for the better quality, quicker curing type.

PU foam is a fantastic material for making costumes and props. it's very easy to carve, mold and shape. It's also very easy to paint and it is also very light strong making it ideal for prop armour and weapons. I understand why cosplayers use it a lot for making prop weapons

Using hot glue to make the hands worked well but once the glue had hardened it is very rigid so it was not really possible to bend the fingers. If I make hands again I will look into into a flexible adhesive or perhaps use molded silicone rubber.

Though the costume looked good it was perhaps not the best costume for an active 9 year old because the big head and extra arms quite quickly became annoying when it hindered play, so it wasn't long before the costume came off.

The alien feet worked great and he wore them for days after the party. The robust PU foam did not break and they are still in one piece.

I enjoyed the build immensely and learned a lot of new techniques with new materials.