It’s inadvertently become a week of highlighting foam armor. I just keep stumbling across helpful tutorials that make foam look like a completely different material, including this one from LadyVengers on Tumblr. The tutorial goes over how to paint foam and takes the material from the picture on the left to the picture on the right. Quite the difference, eh? She used the technique to on Iron Man armor but you can apply it to any build. Materials include craft foam, Mod Podge, Plasti-Dip spray, and a few other items. Not everything is super cheap, but it will last you a while.

The first step is using your foam to make the armor. Once it’s been heat-formed, glued together, and had time to dry you can paint. Then you seal the foam with Mod Podge:

If you have the spray-on Mod Podge, simply spray a few light layers all over your foam. It should make your foam almost looks slightly sparkly when it’s in direct sunlight. After a few layers of spraying, you can skip right to the Plasti-Dip step.
If you have the tub of brush-on Mod Podge, start here. Take your mod podge, your brush, and a glass of water. I usually do this outside when it is really sunny and hot because it’s easier to dry. Dip your brush into the mod podge, then dip it in the water, basically making a half-mod podge, half-water concoction. Then brush it on your foam piece so that your foam is basically soaked in this stuff. We do NOT want brush strokes here- literally make it as watery as possible. It should look like really white water. It might drip everywhere; this is why we do this outside.
Let it dry and soak into the foam, and do about 3-5 layers of this. Use a little brush to move the water around equally on detailed parts, don’t let it build up and dry.

The next step is applying Plasti-Dip, and this is definitely something you want to do outdoors while wearing a mask and gloves.

Shake the can well, and start spraying. It’s better to do a lot of light layers rather than one thick layer. If you spray too much of this stuff on, it’ll start to glob up any details you may have on your armor piece. HOWEVER, spraying it on thick in areas where there is a unsightly seam is a good way to cover it up.
Keep spraying on layers of this stuff until your piece is fully covered and even (make sure to get the edges!). Once it is dry, your foam piece will have a rigid layer of plastic on it.

See the entire tutorial at Tumblr.