“This is just… This is just soft foam and duct tape. It can’t harm anyone.“Role Models (2008)
Choosing the right foam for your costume/prop is probably the first big choice you’ll make in the process. It’s important to know what you want your piece to look like and how you want it to behave when worn/used. If your foam is too thick, you lose that super important flexibility that most armor pieces need. If it’s too thin, it just looks like lame painted foam.
Luckily, there is a plethora of different kinds of foam available to cosplayers. Most of them come in various sizes, colors, and thicknesses, but different types will have different densities, rigidity, and feel.
The first foam we’ll look at is craft foam. Craft foam is cheap and widely available at most brick-and-mortar craft stores. You can find it in just about any thickness, size, and color. The downside to craft foam is that it is far less dense than other foams, meaning it tends to sag and bounce like you would expect loose foam to do. If you are making thick armor pieces that need to appear firm and sturdy, you probably want to pass on craft foam.
Much like Band-Aid, Worbla is actually a brand name, not a general product name. Worbla is composed of thermoplastic resin and wood flour. At room and lower temperatures, it has a solid feel similar to hardened leather. When it is heated, however, it can be molded or sculpted into whatever shape is desired. Even while cooled and solid, it can still be carved or sanded much like wood.
Worbla comes in sheets that have adhesive on one side, allowing you to easily stack sheets or shapes to add depth to your piece, or to form a solid block for carving. The major downside to Worbla is its price. A roll of craft foam that costs $10 would cost about $60 in Worbla.
There are many different varieties of Worbla, including Flame Red Art (flame-retardant), TranspArt (transparent), and Black, which has a smoother, more paint-friendly, surface
High-density polyethylene (HDPE) is another thermoplastic polymer, though it is less commonly used in cosplay. HDPE is becoming more common in manufacturing, specifically in milk and water bottles. It offers more durability for the same thickness of plastic, and as of now is not know to leak any chemicals or carcinogens into its contents.
As far as cosplay goes, HDPE is similar in execution to Worbla, but is much cheaper (free, even, if you are willing to melt down some old bottles yourself). You will need your own adhesive since HDPE won’t have it’s own adhesive side. It will also most likely need to be primed before being painted.
Finally we have EVA (ethylene-vinyl acetate) foam, the most commonly used foam for cosplay and prop-making. EVA foam has a higher density than craft foam, allowing your heavy armor pieces to remain solid and LOOK like heavy armor pieces. It’s also reasonably priced and comes in practically any size, thickness, and color you could need.
The best example of EVA foam that most people will recognize is those interlocking puzzle-piece floor panels. We’ve all seen them in daycares, playgrounds, and trendy offices. Who knew we could actually make some pretty badass-looking sci-fi armor from that? Cosplayers, that’s who. There is also a type of EVA foam called L200 which can be ordered in large rolls and is smooth on both sides.
Those are just a few of the most common foam types used in cosplay and prop making. You can always dive deeper into the rabbit hole if you know what you’re doing. If not, this could be a great place to start.