Tutorial: Create a Round Domed Shield for Costumes

For this tutorial, we will be heat-forming a flat disc of EVA foam into a domed shape (like the Captain America shield). If you’re unfamiliar with EVA foam, I recommend you take a couple of minutes to learn the basics before jumping in. It’s not difficult to use, but it will definitely be easier to understand this tutorial if you know how to use EVA foam, to begin with.

• Learn more about the basics for using EVA foam with cosplay

Supplies needed:

• A large sheet of 8mm EVA foam
• A razor and knife sharpener
• A large domed shape (trash can lid, saucer sled, exercise ball, very large bowl, etc.)
• A heatgun
• Flexible metallic paint
• Craft foam

1. Cut a large circle

Draw out a large circle and cut it out of the EVA foam. I recommend cutting it out of paper first so you can hold it up against you and make sure it’s the right size. I used 8mm EVA foam for this shield, but It would work with 6mm or 10mm foam as well, depending on what you have available.

To make the circle, you can follow the same technique I laid out above:

1. Make a mark for the center point of the circle.
2. Cut a string that is the length from the center to where you want the edge of the circle to be.
3. Tie one end of the string to a pencil.
4. Swoop the string (with the pencil) in a circle around your center point.

When cutting EVA foam (especially when it’s this thick), you also want to make sure you use a very sharp razor, otherwise you’ll get ragged cuts that don’t even go all the way through the foam. Make a habit of sharpening your razor a bit after every cut so that you can keep the edge sharp enough.

Note: Technically, you do not have to create a perfect circle to use this tutorial. You can use the technique to make any time of curved shield, but you’ll probably need to choose a different object to mold the foam against when you get to step 3.

2. Add any surface designs

If you want any designs engraved onto your shield, you’ll want to make the cuts before you create the domed shape. When you apply heat to the foam in the next step, the plastic will shrink just a little bit, causing the cuts you make to spread and create a visible engraved design.

1. Draw your design with a pencil first.
2. With a very sharp razor, cut halfway through the foam following the pencil lines you made.

It’s also a good idea to add any external, glued-on designs before heading to the next step too. This way, when you curve the shape of the shield, the additive designs will follow the shape and curve with it. If you’re doing this, I recommend using contact cement, not hot glue. Any hot glue you use will likely start melting when you use heat in the next step. 

3. Use heat to shape the domed shield

Now it’s time to give your shield some shape. The first thing to do is find a large domed object. The one I used is a large garbage can lid that’s approximately the size of my shield. Other options that I’ve heard of are one of those exercise balls or a saucer disk sled. In a pinch, you can even use the bottom of a large bowl and go one section at a time.

Whatever object you chose, Place the shield face-up onto it. Then grab your heatgun and start heating up the plastic. Be careful not to get the heat too close to the EVA foam, because it will burn (I made this mistake, oops! But don’t worry, you can paint over it).

Since we’re working with thick EVA foam, it can take a bit for the foam to heat up, so try to be patient. You may need to heat the back of the foam as well, to help it get hot and flexible on all sides.

Once heated, the foam will become much more malleable and it will fall to the shape underneath. Hold it in place until the foam cools. You can wear work gloves if it’s too hot for you to touch. As the EVA plastic cools down, it will retain the shape that it cooled in, giving you the domed shield.

Always work in a well-ventilated area when heating EVA foam. The foam plastic releases fumes when it’s heated so you want to make sure you have a window or door open to keep the air clear. It’s also a good idea to wear some kind of face mask to keep from inhaling too many fumes and becoming lightheaded.

4. Paint it

Now the hard part is over and it’s time to paint your domed shield. I recommend using flexible paints when using EVA foam so that it’s less likely the paint will chip. (I’ve had good results with PlaidFX and Liquitex brand paints)

If you want your shield to have a metallic look, there are lots of different metal paints to choose from. Test out the paint on scrap pieces of EVA foam before choosing which one to use on the final shield, so you can figure out what’s shinier and more realistic. Don’t forget, you’ll probably want to add at least two to three layers for full coverage paint.

If you want to completely avoid adding brush strokes to your metal shield, you may want to consider a spray on paint or airbrushing. I don’t have much experience in this area though, so I recommend doing some research on how to use these products first.

5. Add a strap to the inside

After you’re happy with your shield, all you have to do is add a strap to the back so you can hold it. You can paint the back if you want to. I skipped the step since I only intend for the shield to be visible from the front in pictures. Simply cut a strip of craft foam or 2mm EVA foam and glue it to the back of the shield.