Accomplishing the Unlikely

Tutorial: Fiberglass Resin Over EVA Foam

This tutorial will show you how to craft costume armor pieces by creating your initial shape from EVA foam, then casting fiberglass resin over it. The finished product is lightweight, durable, and ranges in rigidity from semi-rigid to fully rigid. It has a hard, smooth look and feel similar to metal. At the bottom of the page is a list of all tools and materials I used here, complete with links to purchase them online.

When working with fiberglass resin, make sure to wear disposable gloves, eye protection, and to work in a well-ventilated area-- ideally, outdoors. If you have sensitive or injured lungs, you should use a respirator.

Prepare your workspace ahead of time with a drop cloth or old towel-- some kind of work surface that can be thrown away in the future. Get a supply of cheap, disposable paintbrushes, as brushes used with fiberglass resin will be single-use. Plan to mix the resin in a disposable container that is NOT lined with wax-- don't mix your resin in paper bowls, as the wax lining will interfere with the curing process!

After mixing the resin and hardener, you will have about ten minutes to work with the solution before it starts to cure. If you're making several armor pieces, you will want to mix fiberglass resin in small batches.

Always dispose of uncured fiberglass resin and anything that has touched it - cloth, containers, paintbrushes, etc - in a garbage bag. Do NOT place resin-coated items in the sink, or rinse them in the sink! The resin will go into the sink pipe and harden there, and you will have to replace the pipe.

If you live in a humid area, you'll need to mix more hardener into your resin than indicated by the manufacturer, and it will take longer to cure.

With those tips in mind, let's get crafting!
Begin by shaping the EVA foam armor piece as you want it. Shown to the left are several basic EVA foam armor shapes.
Cut out pieces of fiberglass cloth that are slightly oversized relative to the area of EVA foam that they will be cast over.

When casting fiberglass over EVA foam, only do angles and/or curves along one axis at a time. Shown to the right are two EVA foam pieces with multiple curves - note that I'm beginning by casting the fiberglass over the curved ends, rather than trying to cast it as a single large piece.

Mix the fiberglass resin with the hardener. If you live in a humid area, it may require up to double the manufacturer's recommended amount of hardener for the resin to fully cure. Apply the mixture to the EVA foam, then press the fiberglass cloth over it. Smooth any wrinkles in the cloth, and apply a second layer of the resin/hardener mixture.

The resin will take 1 to 2 hours to cure. The image on the left shows the armor pieces immediately after the curing process.

Cut away the excess fiberglass cloth and sand the rough edges down. You will want a dedicated pair of scissors for cutting fiberglass cloth, and NOT your fabric scissors - these will get dull and damaged easily! An ideal pair of scissors for this task would be short and designed for flush cutting.

Hobby Lobby carries a specialty fabric scissor which looks like a miniature pruner, and works exceptionally well for this purpose. It will be linked at the bottom of the tutorial.

Now, your product has a hard, durable feel, but it has the rough texture of fiberglass. You want it to have the smoother texture of metal. To achieve this, coat the armor piece(s) with a sealer such as Mod Podge Matte. Spray-on truck bed liners also work for this purpose. Plasti-Dip can be used, but will require several coats to fully cover the fiberglass texture.

Once the sealer is dry, you're ready to paint your armor! I use automotive spray paint for a sleek finish that finalizes the metal look. To make my armor appear battle-damaged, I start with a gloss black base coat and add streaks of steel gray.

To seal the paint and eliminate the tacky texture, I spray the finished product with Mod Podge Acrylic Enamel.
Here is a list of all tools and materials that I use in the process of making fiberglass-over-EVA foam armor. Clicking on any of the items on the list will take you to the relevant page on the vendor's website.