Tutorial: Using Foam Clay for Costume Props

clay 101 for cosplay props

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Foam clay is kind of like plastic clay. It’s a little rubbery and moldable, but when it dries it behaves similarly to EVA foam. EVA foam is a common material used for cosplay prop making. It’s excellent for making lightweight props, jewelry, and armor. However, the flat pieces of foam plastic are not great for creating organic, natural shapes. 

That’s where foam clay comes in. You can mold it on top of your foam prop to add details and build texture on top of the EVA foam base. After the foam clay dries it will still be able to bend along with the prop or armor underneath, but you will not be able to re-wet the foam clay to make it moldable again. Once it’s dry, you can’t go back. (find foam clay on Amazon)

However, foam clay is not as versatile as other kinds of clay. You technically can use it on its own to make small props, but it’s not the easiest clay to work with. It doesn’t stretch as easily as other types of clay and its rubbery texture makes it difficult to create detailed designs, but there is no substitute if you want to use it with an EVA foam prop. 

foam clay horn
Foam clay can be used on top of EVA foam to create a more natural or organic appearance. For example, you can create the ridges on ram horns with foam clay.

When to use foam clay

Pretty much the only time you need to use foam clay is when you’re working with EVA foam. Generally, it will be used to add texture to the surface of your props or armor. However, it can also be used to fill in gaps and smooth out ugly seams in the foam base.

How to use foam clay

When working with foam clay, you will want to use water to make the clay more moldable. Keeping it moist will also prevent the clay from drying out too quickly. Once you’re finished, let the foam clay sit for 24-48 to dry completely before trying to paint or heat-form it.

scoring eva foam
To attach foam clay to EVA foam, score the the clay and EVA surfaces by creating many crisscrossing lines. Then add water to both side and press them together.

Attaching foam clay to an EVA foam base. There are two ways of attaching foam clay to EVA foam, one while you’re molding the clay, and the other after the clay dries. 

  1. While you are molding the clay, you can score the surface of the EVA foam and the piece of foam clay on the spots they will connect (scoring means making many small crisscrossing lines). Then add some water to both sides you’re attaching and press the clay onto the foam surface.
  2. Alternatively, you can create your foam clay pieces separate from your EVA foam base and let them dry. Then glue them onto your foam to attach them after the fact.

Using foam clay with silicone molds. You can also use foam clay with silicone molds if you’re trying to get a specific shape. Simply press the foam clay into the mold, making sure to fill all the nooks and crannies, then allow the foam clay to dry. Afterward, you can glue it to your EVA foam base structure.

Emily Joice

My name is Emily, and I have been cosplaying since my very first convention in 2008. Over the years, I've experimented with all different kinds of cosplay costumes, especially loving the process of creating props and styling wigs. I also delved into cosplay photography, and love exploring how to optimize costumes so they look excellent in photos. Most of the photos you find on this site were taken by me over my years at anime conventions.

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