Introduction: Iron Man Wearable Arc Reactor (3D Printed) 5 Designs

About: --- --- ---

Iron Man is probably my favorite fictional character of all time. It might be because he's a human being without any supernatural powers. He's able to transform and bend his environment around him using the tools that he builds himself. I've always wanted to make an under-the-shirt glowing Arc Reactor, so here it is finally! Whether you're looking to cosplay as Tony Stark or need a last minute Halloween party costume, this project might be for you.

Thanks for checking out my project and if you feel like supporting my work please consider subscribing to my YouTube channel. Thank you!

Total Build Time:
Once all of the 3D-printed parts are printed, you should be able to assemble everything in just 1-2 hours.


Download the 3D-printable files for free from Thingiverse here:

    • Print 1x Light LED Holder / Light Diffuser 1x "Quick Connect" Buckle
    • Print 2x Elastic Connectors
    • Print 1-5x Arc Reactor Faceplates (What's your favorite? Let me know!)

If you don't want to use the same LED lights that I did, I added a "universal" variation of the diffuser that is hollowed out so that you can insert any style of LED lights you may have lying around.

It would be awesome if someone integrated a Neopixel Ring and programmed in some light animations!

I also included some STL variations of the light holder without the "harness tabs" on the sides in case you wanted to build your own custom wearable mounting system.

TIP: Print the transparent light holder/diffuser at 50-65% CUBIC infill (experiment with your slider preview). The cubic infill contains triangular pyramids that help scatter and diffuse the surface mounted LED lights. The larger the triangular pyramids, the more diffused the light!




Step 1: Preparing the Vector Artwork for 3D Modelling

I started by browsing the web for all the arc reactor designs I could find (I know I'm missing a few!).

I copy and pasted photos of different arc reactors in to Adobe Illustrator and then traced over them to create symmetrical vector outlines on top.

For more detailed instructions on how to trace photos into vectors, check out my previous instructable: 3D Printed Stained Glass Effect Suncatchers

I had to improvise a bit on the designs because I wanted to be able to extrude and print all of the faceplates flat and without supports. As a result the designs may not be a "screen accurate" but that's compromise I had to make for more versatility (and time saving).

Once I was happy with the first 5 designs, I exported each individual design as a DXF file so they can later be imported into Autodesk Fusion 360.

Step 2: Modelling the Light Holder in Fusion360

If you want to get started in 3D modelling, I highly recommend starting with Autodesk Fusion 360. It's really intuitive to use and you'll get the hang of it after just a few basic tutorials.

The first step was designing the "Light Holder / Diffuser" part. This is the main 3D-printed part that will house the LED lights and get mounted to the wearable harness.

I started the design using the constraints of the sizes of the lights I had (see the exact lights I used listed in supplies list above). The evolution of the design followed logically from the sizes of the lights, so this made it a lot easier to create the design based on the LED measurements (90 mm outer ring LEDs, 30mm center light bulb LEDs).

I started with my basic circle shapes and then extruded the light holder to about 1cm depth. the rest of the design features followed from there. I added recessed pockets to mount the lights into and then added tabs on the sides for later connecting the elastic straps.

I then added in both vertical and horizontal "tabs" to the left and right sides of the light holder. These tabs contain 1-inch holes to accommodate the 1-inch elastic fabric straps.

Note: In the provided 3D files, there are versions with and without tabs in case you wanted to design your own custom mounting system.

The last features I added were four symmetrical "detent" holes/cavities around the outer perimeter of the light diffuser. The faceplates will have little 'bumps' on them that will snap into those holes and hold them on with friction.

TIP: Instead of exporting as an STL file and waiting for your files to render in the cloud, you can right-click on the top of the object hierarchy and click on "SAVE AS STL". Your computer will generated the STL file instantly!

Step 3: Modelling the Arc Reactor Faceplates in Fusion360

Once I knew my dimensions from the light holder, I could then extrapolate the circumference and determine how wide/thick the faceplates needed to be.

I imported the first Arc Reactor design DXF file into Fusion360 and created the first faceplate.

I then extruded the faceplate to about 2mm (more than enough to block light but not be too flimsy). I extruded an outer perimeter around the circumference of the faceplate to wrap around the light holder snugly.

To really keep the faceplates affixed to the light holder, I added in the little "detent bumps" to the four corners.

After a couple test prints, I made sure I liked how it fit and then just swapped out the design sketches for the subsequent arc reactor designs.

Export your STLs and get ready to PRINT!

Step 4: 3D Printing the 3D Files

Download the 3D-printable files for free from Thingiverse here:

  • Print 1x Light LED Holder / Light Diffuser
  • Print 1x "Quick Connect" Buckle
  • Print 2x Elastic Connectors
  • Print 1-5x Arc Reactor Faceplates

Printing the Light Holder / Diffuser and their Variations

Print the Light Holder with TRANSPARENT filament at 65% Cubic Infill to enhance the light diffusion (100% infill decreases light diffusion). White filament might work too but I haven't tested it.

    This is the primary light diffuser design that includes pockets to mount LED lights and tabs on the side to connect elastic straps for the harness.
    This is the same design as #1 that includes pockets to mount LED lights, however there are no tabs in case you wanted to create your own custom mounting system.
    This version of the wearable diffuser is hollowed out so that it can fit any LED lights that you want to stick inside. It includes tabs on the sides for mounting to a harness.
    This is the same as design #3 except the tabs are removed in case you want to create a custom mounting system.

Printing the Interchangeable Faceplates

Print any of the FACEPLATE files with BLACK (any opaque filament should work). If you want to just use all transparent filament, you can just spray paint the faceplate after printing. 75-100% infill is fine (the walls are thin so it will basically be 100% anyway).

Choose your favorite Arc Reactor style to print, let me know your favorite version in the comments!


Printing the Strap Buckle & Harness Connectors

These are very simple little models for creating the harness - but they work surprisingly well! These connectors are designed to work with 1-inch width fabric elastic straps. Use white elastic straps so they are better hidden under all shirt colors. Print with 100% infill:


Step 5: Installing the 12v LED LIghts Inside the Light Holder

First remove the original plastic light diffuser that comes packaged with the HALO LED ring light. It’s nice, but just adds unnecessary bulk. It should just snap right off without having to damage anything. I also removed the adhesive backing on the backside of the LED ring. Removing the adhesive also removes bulk and exposes the electrical soldering points where we need to connect our leads.

Test fit the LED lights inside the housing and position them where they will ultimately end up.

Now we need to connect the center LED light in parallel with the ring LED light. Measure two pieces of wire to the right length and solder the two lights together.

On the end of the light assembly, solder a male "pigtail" connector on the end to add some modular functionality. This will make it easier to connect and disconnect the power source.

If you have one handy, solder a 9v battery connector to the female "pigtail" connector. In my case I didn't have one so I just soldered the pigtail directly to the battery (if you do this be careful not to hold the soldering iron on the battery for too long - will melt the battery plastic and destroy the battery).

Step 6: Creating the Wearable Elastic Harness

Lightly heat up the side tabs with a heat gun (or lighter if that’s all you have). We are going to slightly bend the tabs so they conform better to the shape of your chest.

Slightly bend the tabs up so they are nice and curved and follow the shape of your chest.

Place the arc reactor on your chest and confirm its a good curved shape. Reheat and bend again if necessary.

Get out your roll of 1-inch elastic fabric strap material. I chose white because it will get hidden the best under any color of clothing (black straps might show up under a white shirt).


Cut a small 10-inch or so length of strap and thread it through both 3D printed connectors as shown. We will call this the “back strap”.


Estimate the side strap length by wrapping the elastic around one half of your body. Snip this length and then duplicate it for the other side of your body.

Thread the left and right side straps into the back strap as shown.

Now thread the opposite ends of either side strap into the light holder’s vertical holes as shown.


Estimate the length of the shoulder straps by draping it over your shoulder and guessing where it might reach the back strap. Snip this length of elastic and duplicate it for the other side of your body.

Thread the shoulder straps through the top horizontal holes in the back strap.

Thread the left and right shoulder straps through the top horizontal holes in the back strap.

Lastly, thread the front ends of the shoulder straps into the horizontal holes of the light holder.

And that’s it! Your harness is almost complete...we still need to test fit it.

Step 7: Test Fitting and Finalizing the Wearable Harness

Carefully put on the harness by placing it over your head.

It might help to have a friend with you to help you with this part. Do your best to not let the elastics pop out!

Pull all of the straps tight and loosen any slack. The straps should be tight but not TOO tight. Adjust the looseness to your personal preference.

Once the strap positions are set, hold them in place with pins and/or mark the positions with a pencil so you can recreate the strap lengths if you need to when you take off the harness.

Remove the harness and start closing up all of the loose-end strap loops by sewing them shut with a needle and thread.

When all of the loops are closed and the straps are firmly in place, find a single spot on ONE of the side straps that is beside your chest and ideally under your arm so the buckle stays hidden. This is where we are going to put the “quick release” buckle.

Mark the position of where the center of the buckle will be on the strap. Once marked, snip the side strap in this spot. Thread both open ends of the snipped side strap into the male and female 3D-printed buckle parts. Once they are threaded in, don’t leave any excess material! Sew these loops shut.

Snip off any excess elastic straps that are hanging off any part of the harness.

Using a lighter, lightly singe/melt the snipped ends of elastic to stop them from fraying or unravelling.

And that’s it! We’re done! Wasn’t that easy? Your DIY Arc Reactor harness is now ready to wear.

Step 8: Putting on and Taking Off the Wearable Harness

Place your left arm through the left shoulder strap and bring it towards your head.

Stick your head through and in between both of the shoulder straps.

The shoulder straps should rest flat on your shoulders.

Position the Arc Reactor mount on the center of your chest where you want it to stay.

Plug in your modular inline LED light switch (link provided in the supplies section).

Plug your 9v battery into the other end of the light switch's cable.

Place your favorite Arc Reactor faceplate on to the light source.

Since this Arc Reactor is meant to be worn UNDER a shirt, place your desired shirt over top.

And that’s it! Let your inner Arc Reactor shine through.

If you want to stop any light bleeding out from the sides of the diffuser, you can simply paint over the sides of the light diffuser to block any unwanted light. Thanks for making it this far!

Step 9: What's Your Favorite Arc Reactor?

I'd love to know what you think and what your favorite design is (and why)!

My personal favorite is the first ever Arc Reactor, the Mark 1 - it just holds a special nostalgic place for me.

Thanks for reading along and please consider subscribing to my YouTube channel!

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