Cosplay Armor: How to Make a Female Chest Plate

If you were making an actual female breastplate, the construction wouldn’t actually be all that different from a standard male breastplate. However, most anime, cartoons, and video games take a lot of creative license with this. So as cosplayers, we need to learn how to create a more complex breastplate that takes our curves into account.

A female breastplate is not the easiest to make. So if this is your first time working with EVA foam, expect to have some difficulties as you learn how to use the material. I recommend getting plenty of extra foam just in case the first chest plate you make doesn’t look as good as you envisioned.

Supplies needed:

• Plastic wrap
• Duct tape
• Scrap fabric or paper towel
• Paper and pencil
• EVA foam (2mm or 4mm)
• Sharp razor
• Contact cement
• Sandpaper or a rotary sanding tool (like a Dremel)
• Heatgun
• Primer
• Flexible paint
• Elastic

1. Create your chest plate cups

In general, I find it’s best to get the bra cups designed first since the rest of the breastplate usually revolves around these pieces. The cups are usually the trickiest part, so if you can get this part right, you’re already halfway there.

1. Take your fabric or paper towel and hold it around your breast.
2. Pinch out darts along the center seam until the fabric will lay flat.
3. Trace the darts and around the base of your breast.
4. Remove the scrap and flatten it out. You’ll see that you created two curved shapes.
5. Clean up the lines and trace this pattern onto paper. Make sure you label the pieces so you can remember which part is on top and where the center is.
6. Make paper mockups to use in the next step. These will help you make the rest of the breastplate.

In the pictures, you’ll see that I’m doing this process on a mannequin, but this is just to make it easier to use as an example. If you can, I recommend you use your own body shape to create your chest plate. Wear the same undergarments you intend to wear for your cosplay and make the design based on your unique chest size and shape. You’ll get a much better fit this way.

2. Wrap your chest in plastic and duct tape

Just like in step 1, I recommend that you wear whatever undergarments you intend to wear with your final cosplay. You want to create your armor in a size that will fit when you are in costume. These next couple of steps will be a lot easier if you get the help of a friend or family member.

Wrap your torso in plastic wrap (not too tightly!). This is just to protect your body and clothing from the tape. If you prefer, you can also use a light fabric or a tight T-shirt that you don’t mind cutting up.

Next, cover your torso in duct tape. You only need to cover the areas that the breastplate is going to cover. So if the chest plate is going all the way to your neck, you’ll need to add duct tape there, but if it includes a lot of cleavage, you can cover a smaller amount.

Avoid wrapping the duct tape around your torso. You don’t want to constrict your breathing while making your armor pattern. Instead, place strips of duct tape on the plastic one at a time. You also don’t want to make it too tight since that could result in a breastplate that’s slightly too small. Make sure the tape is loose enough that you can easily get a scissor underneath it to cut it off.

3. Draw your chest plate design

Before drawing, tape the paper cup designs that you made in Step 1 and tape them to your chest. You’ll be drawing the chest plate design around these pieces.

Use a pen or sharpie and draw the design for your breastplate directly onto the duct tape. Don’t forget to get someone to help you draw the design for the back of your chest plate too.

Once the basic shape is drawn, add cutting lines to create the many pieces of the breastplate. Typically, you will make these lines down the center of your body and along any highly curved areas. You can also take cues from your character’s armor and make separate pieces that match up with their design.

After you’re happy with your design, label all of your pieces. I also recommend snapping a quick picture at various angles, so you remember how it looks when it’s all put together. This will help you reconstruct it correctly.

When that’s finished, you can carefully cut the breastplate pattern off of your body. You can clean up any lines that are a little wobbly and cut all the pieces to separate them.

4. Make a paper mock up

After you’ve cut your pattern off of yourself (or the body form), trace everything onto normal paper. Make sure you label everything! You don’t want to forget which pieces attach where later on. If you want everything to be completely symmetrical, you only need to copy half of the pieces (whichever half looked better).

Then take the time to recreate the breastplate in paper. While this step isn’t strictly necessary, I highly recommend you do this. It gives you the chance to make sure everything is lining up correctly and make any last adjustments to your pattern.

This is also when I like to add tick marks between layers. These little marks will help you line up the pieces later when you’re gluing everything together.

5. Cut out your pattern pieces

After you’ve tested your pattern and you’re happy with how it looks, it’s time to cut all the pieces out of EVA foam. I’m using 2mm EVA foam in this example, but I recommend using 4mm (I just ran out of the 4mm, so 2mm it is!).

Trace all of your pattern pieces onto the EVA foam with a sharpie. If you have a symmetrical design, don’t forget to flip any pieces that are meant for the opposite side. You also want to include all the tick marks and labels when you trace the pieces so that you can keep everything organized.

When you finish tracing, make sure to cut the foam pieces on the inside of the traced lines. If not, the pieces will be slightly larger than your original pattern and won’t match up correctly. I also recommend you use a sharp razor to avoid jagged edges. It’s best to keep a knife sharpener next to you and sharpen the blade frequently.

6. Form your chest plate cups

For this part, all you need are the pieces that will make up your breastplate cups. Make sure the pieces are oriented correctly so that you don’t make a mistake when gluing them together. Apply contact cement to the inner edges and wait 5 minutes for it to get tacky.

Starting at the center edge, press one set of cup pieces together. Carefully press the seam together until you get all the way to the opposite end. Line up any tick marks that you made as you go. The contact cement should give a fairly good hold almost immediately.

You can use other types of adhesive if you want to, but I recommend using contact cement for this part. It gives a very good hold between the EVA foam pieces and won’t melt in the heat (like hot glue does).

7. Glue your chest plate together

Use contact cement to glue the rest of the chest plate together. I like to organize the pieces and get them lined up before I start gluing. This way I’ll know exactly which pieces go where, and I’ll be less likely to make a mistake.

You can assemble the pieces in whatever order you like. I put the pieces from each side together, then added the cups. After each side was fully assembled, I attached them along the center seam. 

For most of the pieces, you want to attach them along the thin edge of the EVA foam. However, with the cups, attach the edge of the other pieces along the side of the cup instead of trying to match the edges. This will allow them to create bigger bumps on the chest plate.

8. Sand the seams and edges

Once everything is glued together, wait a couple of hours before moving on to give the contact cement enough time to do its job. When you’re ready, move on to sanding. I recommend using a Dremel for this step since it makes the process go a lot faster, but regular sandpaper is always an option.

The goal of sanding is to make the glued seams as smooth as possible unless you want them to be visible as part of the design. You’ll also want to sand the sides of the armor if you made any mistakes or ragged edges while gluing or cutting the pieces out. Sanding can also give the EVA foam a more finished look all around.

Safety tip: When sanding EVA foam or heating it, wear a dust mask and goggles to prevent yourself from inhaling fumes, breathing the dust particles, or getting them into your eyes. You should also stay in a well-ventilated area. Avoid sanding or heating EVA foam around any pets.

9. Heat form the breastplate

When you’re finished sanding, the EVA foam breastplate will still look pretty flat and lifeless. This is where heat comes in. You can heat up EVA foam and hold it in place when it’s hot. As the foam cools it will stay in the shape you’re holding it, making it possible to fine-tune the shape of the chestplate.

You can easily make the EVA foam breastplate curve around your body by using a heatgun:

1. Heat up the EVA foam. You’ll notice the foam becomes a little less rigid when you do this. Avoid holding the heatgun in one place for too long, or you’ll risk burning the foam.
2. Hold the heated foam against your body. This will allow it to cool into the shape you need to fit the breastplate. You can do one part at a time, or reheat the foam as many times as necessary.
3. As the foam cools next to your torso, it will stay in that shape. Keep holding it in place for a minute, or until you feel the foam cool down. When you take your hands away, it will stay in the position you put it. You’ll now have a curved breastplate.

Don’t forget to also repeat this process for the back of your breastplate.

10. Prime and paint the breastplate

Give your armor 1-2 layers of primer to help seal it before painting. This also helps to smooth out some rough or uneven patches if you didn’t feel like sanding everything.

Since the breastplate will end up bending and moving while you’re walking around, I recommend using primer and paint that are flexible when they dry. This will prevent any cracks and chips in the paint. For primer, I recommend Cosflex or Flexbond. There are a lot more choices for flexible paint, but the ones I’ve tried are Liquitex and Plaidfx, and they both seem to work well.

You can, of course, embellish the armor with any kind of added design, engraving, or painted pattern that you want. This is just a basic tutorial that you can use to design your own unique armor.

• Learn more about how to make your armor look metallic
• Learn more about how to make your armor look like leather

11. Make the chest plate wear-able

The easiest way to attach the breastplate is by using elastic. However, there are any number of ways you can go about making this armor wearable. You just have to remember that the armor doesn’t stretch, so you need to make sure you can get it over your head.

To add elastic all you have to do is cut four short pieces of elastic and glue them to the inside of the chest plate front and back to connect them. I used hot glue for this, but you can use whatever kind of glue you want. Try on the chest plate and make sure it fits and the elastic stretches enough to get over your body.

Other options that you can try are:

• Attaching the armor directly to your bra.
• Using a velcro closure
• Adding a hook and eye
• Making it lace-up, corset style