Never tried epp foam, but, when covering other foam it's either really tight or wrinkly. Might need spars or stiffeners in the wing if it's flexible type of foam or wings can flex a little to much causing wrinkles on one side or the other. Have to be carefull of temp as well. As I say, never used epp foam, but on other foams, it can suddenly melt without warning and those melted spots will show up as wrinkles in the covering. Good luck with your project though, sorry I can't be of more help for you.