Picture of The 15-dollar, 15-minute Arc Reactor.
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There are a bevy of good (some great), detailed, extensive Instructables showing you how to make a near-screen-accurate chest arc reactor for a Iron Man/Tony Stark costume.

I appreciate and enjoy all those but they can be a little time-consuming/expensive/requiring skills you may not have.

So I made this one for under $15 and in under 15 minutes. It's perfect if you need to throw together a costume but don't have a lot of time and/or money (or, in my case, craftsmanship skill).

Here's all you need:

1. A battery-powered, short string of blue LEDs (example: http://www.littlebrightlights.com/site/1435548/product/AC-100B). My string was Philips brand, 3 feet long (if I remember correctly) with 18 lights but really, any brand and any amount of lights under 20 would probably work just as well -- I got mine at Target for $8. Each of my individual lights are just about 1/2-inch long and 1/8th of an inch across. Try and find lights that are on a string of a shorter length, with as little space between bulbs as possible (this information should be on the box). The lights are the most important thing, not the length of the cord.

2. A hockey puck-shaped piece of white Styrofoam (1-inch thick, just under 3 inches in diameter). I got my piece by cutting the bottom off a conical piece of craft Styrofoam I already had. Packing Styrofoam will probably be too brittle to cut and it also has less opacity/reflectivity. I'd recommend using the lighter, craft Styrofoam that has the crystallized look and is made to be cut (Michaels is a good option).

3. A pen or marker.

4. A toothpick.

5. Tape (glue would work, too). I used 2-inch wide clear packing tape but any kind would probably work.
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MorganV13 months ago
Did the battery pack already come with the lights?
JustinBrown (author)  MorganV13 months ago
Yes, they were attached! I didn't do any rewiring or anything requiring electrical know-how.
lisa.rimke10 months ago
Made this for my 4 year old son's costume and he loves it!
It's large, but whatever, still cool looking :)
Grafx4Life10 months ago
Finally done. Probably took closer to 4 hours due to changes I had to make, but I'm pretty happy with it. Thanks for the Instructable!
Grafx4Life10 months ago
I have everything I need but I'm too tired to build it tonight. Bout a 9 ft string with 36 lights but they are really small, so I might double them up. Or maybe I'll check Target. The link you provide for you lights is no longer working.
ehhdean1 year ago
Not bad. I may add this to my suit next time. I need a more powerful light.
sequret963 years ago
http://www.youtube.com/watch?v=afsn71yqTP0 heres mine
missmaggy2u3 years ago
One question. When you hang it over your shoulder, how does it stay in the center of your chest?
mhkazemi3 years ago
that is good idia
reality good
you can develop it
think about!!!
carellano13 years ago
Loved this instructable and did my own. Could only find a 10 led string so my arc reactor looks more like the prototype he first made in the 1st movie. The cord was too short though so i cut it and and soldered longer wire to the battery pack so i can put it in my pocket. Used the leftover wire to hang it around my neck. Lemme know what you guys think :)

JustinBrown (author)  carellano13 years ago
This looks rad. Great work, sir.
hey man thats awsome!
Hey Justin I have a question, I don't know if its because you made this a year ago, but i could not find the right lights that you used from target also would the lights from (http://www.littlebrightlights.com/site/1435548/product/AC-100B ) work just as good without me having to change the size of the foam circle?

And finally, what color lights would be more noticeable under a suit?

I'm going to be Tony Stark :D
JustinBrown (author)  dominicgrz133 years ago

Those LittleBrightLights look good to me, you might just have a bit more slack wire, with a six foot string. I used blue lights and those seemed to work very well but I think white would generally be fine, too.

Thanks for the question.
Oh, OK cool thanks bro.
JacSpark3 years ago
Would it be possible to use the LED "throwies" idea? but just stick them inside the foam?
JustinBrown (author)  JacSpark3 years ago
Sure, I don't see why not.
tparikka4 years ago
looks great
pretty cool brother
Doctroid4 years ago
There's a ton of arc reactor instructables but this is the one I was most inspired by. I decided to do it Wednesday night, bought the materials and made it on Thursday, and wore it on Saturday. Being short on time (at the same time I was scrambling to finish up my son's bounty hunter costume), the simple behind-the-shirt approach seemed the way to go.

I did it differently though. I used a plastic jar lid with holes poked in it, covered with clear plastic with wax paper behind it to diffuse the light some, and with electrical tape in a circular grid over that to make the light pattern more like what was in the movie. I used 12 lights -- 10 in a circle on the outside and 2 in the center. (I cut the others off. Turns out with the LED strings sold at Target you can cut off an even number of lights and have the rest still work -- if you cut off an odd number, the last remaining one won't light up.)

For clothes I wore an a-shirt, a brown military shirt, and a military style cap, all reasonable approximations to things Stark wore in the cave in Afghanistan in the movie though not in that particular combination. I hot glued string to the arc reactor to suspend it from my neck and secure it around my chest, with the batteries inside my waistband. Worked pretty well and was easy to put together.

The arc reactor is too low on my body in the picture, I know -- as soon as I saw it on the camera screen, I went and re-adjusted it higher!
JustinBrown (author)  Doctroid4 years ago
Wow, Doctroid -- this looks great. I'm glad I could inspire you and help with a costume.

I just wanted to thank you! I just made this. It was so easy. It looks great and my boyfriend is going to love it! :) you saved our Halloween! I used LED micro lights from Target. They were 5.99 and they're battery operated. The foam discs I bought at the dollar store in the fake flower section. YAY! :)
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JustinBrown (author)  smallstrangegod4 years ago
Whoa, awesome! I'm glad I could help and it looks like you improved my design. Kudos, m'lady.
Not to rain on the "simple-parade" but wouldn't a dollar store round closet led disk work just as well?  they compress in the middle and light up (so all you see under the shirt is light)  and the back is adhesive (if you're into that, my chest hair isn't so much)   I used this exact set up for the 1st movie and it work out perfectly...just putting this out there.
i did that but i taped some of it of so it had the arc reastor pattern of light
JustinBrown (author)  Green_Primus5 years ago
Yes, I fiddled with the closet disk idea. But I found it to be relatively dim and didn't quite have the same effect.
Burnsides5 years ago
 Where does one purchase the lights needed for this? What section of the store would these be in?
JustinBrown (author)  Burnsides5 years ago
 I got mine in the Christmas lighting section at Target. If it's not around Christmas time, I imagine that some hardware/outdoor stores like Lowe's or Home Depot may have some. Otherwise, the Internet is probably the best bet.

But they're just simple LED lights that you would put on a Christmas tree or to decorate your house around a holiday.
 Ok, thanks!
sorry dude but the arc reactor lights are like a wheel with lines going through it with a circle in the center
JustinBrown (author)  andrewreases6 years ago
15 dollars, 15 minutes. Close enough for hand grenades.
i agree on the hand grenade policy ;)
the others are prettier but couldn`t be done in the short time frame
i think it looks just fine for the application
JustinBrown (author)  Apollo7075 years ago
Here's a dude who gets it.
thank you ladies and germs, don`t applaud, throw money ;)

 Awww. You don't except credit cards?

cprocjr5 years ago
 Not as realistic looking as it cool be, but good enough to work! 
I thought about making some of the other (more complex/accurate) ones, but I didn't want to spend the time. I might actually make this one! I just need to find some light...
XWXAXDXEX5 years ago
AWESOME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I'll get right to it.
itak3655 years ago
That's a pretty awesome jacket, by the way. Good job with the arc reactor
have you heard of indy mogul justin
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