Many anime and video game characters have a chest plate as part of their costume design. This tutorial will go over the basics for creating your own breastplate with EVA foam. You can add as many details as you want to create a more complex shape, but the basic construction will be the same.
If this is your first time working with EVA foam, a breastplate might be a little bit of a challenge. However, it’s absolutely something that you are capable of doing, especially if you start with something fairly simple.
This tutorial will require some basic understanding of how to use EVA foam. I try to explain everything along the way, but it may be useful to check out this beginner’s guide to EVA foam before getting started.
This page contains affiliate links. As an Amazon Associate, I earn a small commission from qualifying purchases.
Supplies needed:
- Plastic wrap
- Duct tape
- Paper and pencil
- 4mm EVA foam
- Contact cement
- Sandpaper or a rotary sanding tool (like a Dremel)
- Heatgun
- Primer
- Flexible paint
- Elastic
- Hot glue
1. Wrap your chest in plastic wrap and duct tape
To start with, you’re going to want to wear whatever undergarments you intend to wear underneath your cosplay. Whether you’re flattening, or bulking up your chest, you want to create your armor pieces in a size that will fit when you are in costume. (there will be some leeway if you use elastic to put the breastplate together, as I’ll show you at the end of this tutorial)
Loosely wrap your torso in plastic wrap. The purpose of this is to protect your body and clothing from the tape, while also giving the chestplate pattern a base layer. So, if you prefer, you can also use fabric or a tight T-shirt that you don’t mind cutting up.
Next, you are going to cover yourself 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 hips, you’ll need to add duct tape all the way down, but if it’s ending at your waist, you only need to cover that far.
To do this safely, make sure you do not wrap yourself too tightly. You should never wrap the duct tape around you since that can constrict your breathing (and make the breastplate pattern too small). Instead, place the tape over the top of the plastic in strips until everything is covered. You want to make sure it’s loose enough that you can get a scissor underneath to cut the plastic and duct tape off later.
As you can see from my images, you can also use a dress form to help you with this step. You’ll probably require one for the back of the armor if you don’t have anyone to help you. It’s not going to give you quite as perfect a fit as if you make your pattern on your own body, but it’s usually good enough.
2. Draw your breastplate design
Now that you are covered in plastic and duct tape, you should use a Sharpie to draw your design directly onto your body. This step is a lot easier if you have a friend or family member who can help you, especially for the back of the breastplate
Typically you will make cutting lines down the center of your body and along areas that are curved to create separate pieces that you will glue together later. This can be as simple or complex as you want.
If you are going to have any pieces that come off of your body, make a mock-up in paper and tape it in place. In my case, I’m making a neckband that comes upward out of the breastplate. To make sure it fits, I cut it out of paper and added it to the mannequin to make sure it worked.
After you’re happy with your design, label all of your pieces and create tick marks between them. I also recommend snapping a quick picture at various angles, so you remember how the pattern is supposed to look. This will help you reconstruct it correctly and keep you from getting confused about which piece goes where.
Then cut the pieces out along your lines and trace them onto normal paper. Clean up the lines as you go. If you want everything to be symmetrical, you can choose which side you like better and just use those pieces (mirroring them for the second side). These are the finished pattern pieces that you’ll use for your chest plate pattern.
You may also want to add a little edge to pieces that will be overlapping each other. For example, I intend to have the side pieces overlap the center piece on this chest plate. So I extended the center piece and added dots where the side pieces should connect.
Before moving on to the next step, you may want to make a paper mockup of your breastplate armor. Cut out your pattern pieces and tape them together to make sure everything fits as expected.
3. Cut your pieces out of EVA foam
Trace all of your pattern pieces onto the EVA foam with a sharpie and cut them out. Don’t forget to flip any pieces that are meant for the opposite side, so you can create symmetrical pieces. When you cut the pieces out, cut on the inside of the marker lines you created. Don’t forget to add any tick marks and labels that you included on the paper pattern pieces.
Tip: Use a sharp razor to cut out your pattern pieces to avoid rough, jagged edges. It’s useful to have a knife sharpener available since EVA foam can dull the edge of a razor quickly.
Everyone will have their preferences when it comes to the thickness of EVA foam to use. I recommend 4mm foam for the chest plate (and most armor pieces). However, you can use 2mm if that’s what you have available, or 6mm if you want to create armor that is thicker and sturdier. In my experience, 4mm tends to be the easiest to work with, while also not being as flimsy as the 2mm.
You will want to cut some pieces with beveled edges so that when they are put together, they make a corner. For example, the neck piece that I’ve added on has a sharp corner on the front, so I need to cut that side at an inward angle to make it form a corner.
4. Glue your chest plate together
To glue the chest plate pieces together, I recommend using contact cement. This will give you the best hold while also remaining flexible and not melting in the heat. If you’ve never used it before, you use contact cement on both edges that you’re gluing together. Once applied, wait 5 minutes for it to get tacky before attaching the two pieces.
When the two pieces are ready with the contact cement, start at one end, and press the edges together. Work your way along the seam, lining up the tick marks as you go until you finish with the other end. The contact cement gives a good hold pretty much immediately, but it’s best to wait a few hours to make sure it’s completely adhered before moving on to the next step.
If you are overlapping any pieces, the process is still the same: apply contact cement to both sides and press them together. The only difference is that you won’t be trying to line up the edges precisely.
5. Sand the seams and edges
Now it’s time for a whole lot of sanding. You want to sand all of the seams you just made so that they are smooth and not so obvious on the final armor. You can use actual sandpaper if you want to, but you can also speed up the process if you use a Dremel (electric sanding tool). It’s not that expensive and it can make sanding take only 10-15 minutes (as opposed to a few hours).
You’ll also want to sand the sides of the armor if you made any mistakes or ragged edges while cutting the pieces out. Sanding cans also give the EVA foam pauldrons a more finished look all around.
Safety tip: When sanding EVA foam wear a dust mask and goggles to prevent yourself from inhaling 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.
6. Heat form the breastplate
Next, it’s time to fine-tune the shape of the chest armor. Right now, the armor is flat and lifeless. Yes, it’s flexible enough to bend into the right shape, but it’s not curving quite like you expect it to.
This is where heat comes in. You can heat up EVA foam to create curved shapes. Hold the foam in place when it’s hot, then as it cools the foam will stay in the shape you’re holding it.
You can easily make these tweaks to the shape with EVA foam if you use a heatgun:
- 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.
- Hold the foam in the shape you want it to be. In this case, you’ll want to hold the foam against your torso to get it curving just right around your body.
- As the foam cools, it will stay in that shape. Keep holding it in place for a minute, or until you feel the foam cools down. When you take your hands away, it will stay in the position you put it. You’ll now have a curved breastplate.
- Repeat as necessary. If you’re not happy with the result, you can reheat the armor and try again as many times as you want.
Safety tip: Always stay in a well-ventilated area when heating EVA foam. It gives off mildly toxic fumes when it gets hot. You may also want to wear a face mask, especially if you find yourself getting a headache.
7. Prime and paint your armor
By now, your chest plate is more or less finished. All you have to do is paint them and attach the front and back. Start with 2-3 layers of primer to give the paint a better surface to sit on. This is especially necessary if you want the final armor to have any kind of metallic sheen to it.
Paint and primer that are flexible when they dry are best to use with EVA foam. This way the paint won’t chip and crack as the foam pieces shift around when you’re putting it on and wearing it. Good primers to use are Flexbond or Cosflex. For paints, I’ve used Liquitex and PlaidFX, but there are many other brands you can test out as well. (many flex paint brands have latex in them, so be aware of this if you have a latex allergy).
- Learn more about how to paint your armor to look like metal
- Learn more about painting EVA foam to look like leather
8. Connect the front and back to make it wear-able
There are any number of ways you can attach the breastplate and make it wearable. You can use velcro, snaps, or even zippers. In this case, we’ll be using elastic. Personally, I think this is the easiest method.
Cut four short pieces of elastic and glue them to the inside of the chest plate pieces 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.
