Oya vod!
Thanks for your question.
The issue with EVA foam is that it simply is not stable enough to support multiple events in a given kit.
That said, fiberglass reinforced EVA foam can have a host of potential issues.... mostly in smoothing, sanding and time spent. EVA foam, simply put, would require multiple layers of resin in order to get the necessary hardness. The issue is how porous EVA foam is. Even High Density Foam has a porous surface that would absorb more of the resin than absolutely necessary; thusly making it not only heavier, but subsequently wasting many of the resources and money you've spent.
The better coarse of action here would be to replace the EVA foam with card stock, like is done when using Pepakura. If you are going to use EVA foam on your kit; use it as padding. You can use EVA padding on the inside of your helmet in order to get a good fit and comfort, you can also use EVA foam on the inside of your gauntlets if it is difficult to size them without throwing off the entire gauntlet.
If you decide not to go this route; to get the look of heavy style plates; 6mm and 10mm sintra are the best to work with. You can also layer 3mm sintra to get the look of trauma plates. 3mm sintra is easier for beginners to work with, and if you have done work with EVA foam and other thermoplastics like worbla, the learning curve is significantly less. Sintra is also significantly less expensive than resin, fiberglass and worbla.
TL:DR - yes fiberglass over EVA could be made approvable, but there's much easier and cheaper ways to build a mando.
Hope this helps!
