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How to build an Arc Reactor

How to build an Arc Reactor

Tony Stark arc reactor costumeI wanted an amazing costume this year

This costume had to be stylish, and it had to show off my engineering skills.  Knowing that, what better costume could I have picked than “Iron Man” Tony Stark?  To make this costume, I needed an Arc Reactor.  Now, by popular request, I will show you how I did it.

The first step is to choose the LEDs you will use.  I purchased this set of surface mount LEDs from Mouser.  I chose them because they were small—which helped later—and because they were bright.  The information that is important for the circuit is that they have a max forward voltage of 3.3 volts, and an operating current of 20 mA.

Using this information, I used an online calculator to determine what resistors I would need.  I used the inputs of 9V for my source, 4.1V for my forwarding voltage (brighter!), 20 mA operating current, and 20 for the number I planned to use.  The output of the calculator showed me I needed ten 47 ohm resistors, and showed me the appropriate circuit to design them with.

The next step was to gather the rest of my materials.  Off to Radio Shack!

I bought a simple board, some 22 gauge wire, the resistors mentioned above, a soldering gun, solder, flux, and some ceramic-covered copper wire.  From Lowe’s, I bought some Plexiglass, duct tape, and some super glue.

Materials needed for arc reactor

Materials needed for arc reactor. This information (c) 2009 Stark Industries

Once I had everything ready, I started building my circuit.  The key to this step was to plan out the LED and resistor locations such that they ended up being evenly spaced, yet still allowed access for the rest of the circuit. Aside from that, keeping track of where all the connections should go proved to be somewhat tedious.  Despite being careful, I still ended up with some gobs here and there that weren’t really the nicest.  To top all of the soldering off, I ended up with a loose connection in my final product so two of the LEDs would flicker. If you’ve never soldered before, I would recommend practicing for quite some time before starting on the final circuit.

Circuit design for Arc Reactor costume

The works

The next steps were to cut the Plexiglass into the shapes that will become the visible portion of the arc reactor.  I needed three pieces: the base layer, which was a circle the same size as the circuit, a ring shape to go over the outer ring of LEDs, and a smaller circle to become the center section of the arc reactor.   I used a carpenter’s knife and a lot of patience to make these pieces.

Design of the arc reactor costume

Starting to come together

Once the plastic was cut, it needed to be roughed up with 220 grit sandpaper so it would diffuse the light from the LEDs rather than letting them shine straight through.  I used a blue highlighter to give the reactor the right hue.  Then, using the ring and center section as a template, I cut out a ring of duct tape to make the reactor look metallic.  I also laid out some strips of duct tape between the LED’s.  Using the bare copper wire, I wrapped a tight layer around the ring shaped Plexiglass piece that would match up with the duct tape.

Working Tony Stark arc reactor costume

It works!

Once the pieces were ready, I super-glued the circuit, the base circle, the ring, and the center circle all together.  This entire thing was then carefully wrapped in metallic duct tape.  Finally, I used some of the basic circuit board material to make a twist tie clamp to attach it to my shirt.

The end result was an arc reactor that drew looks and was easy to manage as a costume!


  1. Bandrik
    Bandrik The Arc Reactor & Tony Stark costume was freaking amazing. I'm so glad you did all this for Oktoberfest, and I'm even more delighted you walked us all through the steps in this article. Many kudos to you, Ryan! :D
  2. RyanFodder
  3. Annes
    Annes *ahem* UNF.

    (that is all)
  4. UPSLynx
    UPSLynx You should keep sunglasses and dark goatee on at all times, it's a sharp look for ya.

    Pretty awesome effort in constructing that thing.

    Plus, it makes your beer glow IMG_1202.JPG
  5. WagsFTW
    WagsFTW Was so cool. Didn't realize you completely constructed it from scratch like that! Kudos! :)
  6. alpsayin
  7. RyanFodder

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