Make an Iron Man Arc Reactor

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Picture of Make an Iron Man Arc Reactor
I didn't have a lot of time to make a great Halloween costume this year so I figured I'd do something relatively simple that was still eye catching and cool. I wanted my Arc Reactor to look pretty realistic, but not necessarily 100% movie accurate, so it's kind of a cross between a MkI and MkII version. There are some things I'd change on the next version (and I'll point them out) but overall I'm pretty pleased with it.

The reactor is attached to an old heart rate monitor strap and it's powered by a 3 volt battery pack that just slips in my jeans pocket. It's light weight and is comfortable to wear for several hours at a time. In the photos below you can see how bright it is- it easily shines through my t-shirt under normal office lighting conditions and is very bright at night.

Follow along and see how it's made.....

Update: see page six for the new style reactor!

Another update! Many people have asked for a kit and a fellow RPF board member has produced a fantastic kit and said I could post a link. This is a very nice kit for anyone wanting to build a wearable arc reactor-
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alopez741 month ago
Does the metal ever get rusty?
Honus (author)  alopez741 month ago
Not if you use stainless steel. Otherwise just spray some lacquer on it to protect it.
fbwman15474 months ago
Could you post a list of all the materials that you used in the second build please? Great design by the way, really inspired!
Honus (author)  fbwman15474 months ago
The outer casing and center ring are turned Aluminum, the back plate and spider are thin stainless steel sheet (22 gauge I think) and the LEDs are the same as used in the first reactor. The lenses are acrylic just like the first reactor but I used a thinner 26 gauge magnet wire to wrap each section. All of the small brass bolts are size 0-80 thread. The circuit board material is the same as the first reactor but I added some small 100 Ohm surface mount resistors to protect the LEDs.

If you have any other questions just let me know!
fbwman1547 Honus4 months ago
Where were you able to customize those aluminium parts?
Honus (author)  fbwman15474 months ago
I made them at home- I have a small bench top lathe. There are some online services that will machine parts for you like Big Blue Saw or you could try maybe a local Techshop or hacker space.
lmeyers35 months ago
hey Honus i am planning to build this as a school project for my end of the year assignment and i am wonder what is the ring of clear maybe plexiglass? im not sure please respond.
Honus (author)  lmeyers35 months ago
Yep- you can plexiglass/clear acrylic to make the ring. If you have any other questions just let me know!
lmeyers3 Honus5 months ago
Hey im at the point where i need the LED's and i was wondering what did you use for lighting i was thinking of using NeoPixels so i can change the colour based on the voltage iw as just wondering what you used and how u got it to look so damn good haha

Honus (author)  lmeyers35 months ago
I used surface mount LEDs- the exact LEDs are listed on the tools and materials page.
game2freak285 months ago
How long did it take you to get all the parts and put it all together
Honus (author)  game2freak285 months ago
I think maybe one week. I had most of the materials on hand.
dadema6 months ago
Hey Honus I love these designs but I'm running into a couple problems.
One thing is that it would be great if you could include a wiring diagram because my circuitry is rusty. Secondly I am using tin snips to cut out the spider legs and it's proving to be quite a challenge because of the minuteness of the leg. Are there any tips you have? Thanks
Honus (author)  dadema6 months ago
For circuit diagrams for LEDs check out

You can enter in any value you like for battery power and LEDs and it'll give you a simple wiring diagram.

Tin snips are hard to use because the metal tends to curl at the edges. For cleaner cuts use a jeweler's saw or nibbler tool.
ssmith1757 months ago
what is the inner diameter of the clear acrylic ring ??
Honus (author)  ssmith1756 months ago
The inner diameter is 2.65" - the drawing shows the outside diameter is 3.15" and the wall thickness of the ring as shown in the cross section is .25" so subtract .50" total from the outside diameter.
ssmith1757 months ago
How did you cut the slots in the slot ring.Can u plss name the tool. And what to do if i dont have surface mounted LED's plss reply fast i need to make this before 25th sept .
Honus (author)  ssmith1757 months ago
Most all of the metal parts were cut using a jeweler's saw. If you don't have surface mount LEDs then you will have to adapt the design to fit a different type of LED- maybe try drilling holes in the clear ring and insert the LEDs.

Please be patient- I'll try to answer questions as quickly as I can. Right now I'm dealing with flood damage from a brutal storm here in Boulder County so I may not be able to answer questions right away.
ssmith175 Honus7 months ago
can we put normal LED's .Does it affects the light of the reactor ??
Honus (author)  ssmith1757 months ago
I don't know for sure- you'll have to try it out and see how it works. I would first measure the height of the LEDs to see if they will fit.
ssmith1757 months ago
Can u tell what was the thickness of your both acrylic sheet??
Honus (author)  ssmith1757 months ago
Those dimensions are shown on the drawings.
ssmith175 Honus7 months ago
ok Thanxx :)
ssmith1757 months ago
Hey Honus, can u plss upload a video of it .
Honus (author)  ssmith1757 months ago
Sorry I don't have a video if it.
This looks awesome and I'm going to have a go at making one, but I need to ask about how expensive it is to make? (I already have the tools available)
(removed by author or community request)
Honus (author)  ClockworkPheonix7 months ago
The sheet metal listed is 22ga sheet steel, which is about .5mm thick. You can use whatever metal you like- the type of metal and thickness I used is just what I had on hand so it's not critical. Regarding the cost, I used a lot of materials I already had in my scrap box but it will probably cost under $100 if you have to buy everything.
Sorry 'bout the stupid comment about the metal, I misread it! (I'd lost my glasses...) But thanks for your help,
If you make it can I just buy one from you?
Honus (author)  marcdowneystark9 months ago
Sorry but I don't sell them! In the instructable there is a link to a kit you can buy.
gcharlow10 months ago
But that would mean there is two wires from the etches and one for the center, I'm really just confused on how the center works with the whole thing
Honus (author)  gcharlow10 months ago
You're over thinking it. It's very simple- all of the LEDs are connected in parallel. Because of this you need one wire for positive and one wire for negative to connect the center LED to the outer LEDs. Does that make sense? Then you need two more wires to the center LED to connect your battery. The power then flows from your center LED to the outer LEDs.

A solder pad is just the copper part that the LED is soldered to.
gcharlow10 months ago
Oh and how do u make a solder pad
gcharlow gcharlow10 months ago
or do I not need one
gcharlow10 months ago
Thank you, I accidentally already did it chemically and am curious of how to make one trace positive and the other negative. Also on your second paragraph u say that I drill holes in the traces and that those wires connect to the battery, I've read that paragraph over several times now and am still confused
Honus (author)  gcharlow10 months ago
I don't understand what you are saying. You don't make the trace "positive" by etching it. You make it positive or negative by the way the battery is connected to it.

The second part is easy. Drill a hole through the copper trace. Insert a wire through the backside of the PCB and solder it to the trace. It doesn't get any easier than that.
gcharlow10 months ago
i am so much more confused now, on the diagram you have a battery but in the pics you have a wire connecting it to a battery pack, can you please explain to me what to do in great detail
Honus (author)  gcharlow10 months ago
You have a positive and negative copper trace for the positive and negative LED solder points. I cut the copper traces using a Dremel tool- I did not etch them using chemicals. The positive and negative traces of the outer LED ring are connected to the positive and negative traces of the center LED using two pieces of wire that are on the BACK of the PCB. These are clearly shown on the LED wiring schematic. You simply drill holes through the traces, poke the wire through from the back of the PCB and solder it to the copper on the front.

Now drill two more holes through the traces for the center LED- one for positive and one for negative. Insert two wires into these holes from the back of the PCB and solder them to the traces- these are the wires that go to your battery. Again, this is shown on the LED wiring schematic. Does that make sense so far?

Regarding using resistors: the first reactor I made did not use resistors and the second reactor I made did use resistors. On the first reactor the battery voltage for the battery (single cell LiPo) I used was 3.7V and the forward voltage drop of the LEDs used is between 3.5V and 4.0V so the resistor value would be between 1 Ohm and 10 Ohms- a very low value so I elected not to include them.

On the second reactor I made you can see there are 100 Ohm resistors soldered on the copper traces. In this case I used resistors because the power supply I was using output 5V, which is a bit higher than the forward voltage drop of the LEDs. So let's say you wanted to power your LEDs using 3 AA batteries. If you are using alkaline batteries your battery voltage would be 4.5V- you could probably get away without using resistors but you would probably burn out the LEDs pretty quickly (exactly how long I have no idea.) If you used NiMH batteries your voltage would be 3.6V and your LEDs would last longer. If you tried to use a 9V transistor battery you would fry your LEDs.

The bottom line is that adding resistors will lengthen the lifespan of your LEDs and they are an absolute must if your battery voltage is higher than your LED voltage drop. While you can get away without using resistors it is considered proper practice to include them. If you look at the resistor calculator page I linked to it shows you how to wire the LEDs using resistors. This is also shown on the new style reactor page- you can see where the copper traces are cut that allow the resistors to be soldered to the LEDs.
gcharlow10 months ago
ok so i have done the inner ring assembly. now i have to do the backplate. I am a litttle confused. I know how to ectch the traces with the printing and ironing and soaking and acetone, but i am confused on how the circuit works. So can you please give me a detailed step by step of how to wire through the back and how to solder the Leds, like why do i need a solder pad for the center and not the outside ones, or do i do that too. And how does the center led connect to the outside ring LEDs and what is the wire you show in the picture. im confused and do i need a battery pack. Please give me a detailed step by step for this part and please give me a list of any addditional tools i need for this part. Thank u

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