Both Depron and the fan-fold or blue foam are housing insulation. Look at your building supply store, not sure if it would even be carried in more temperate climates. You need something roughly 6mm thick, I'm afraid Styrofoam would be too flimsy and crumbly.
stereophone = styrofoam... I totally missed that... no problem Bro - I'm sure your English is better than my Spanish.
We cut wings & fuses for combat planes from foamboard insulation - which is a specific type of styrofoam - pink or blue & higher density. If that is what you're looking at - you can build a plane with it. But it's a different type of construction than what I'm guessing you're after... probably not suited for an electric foamy. But good for glow! Chuck is right though - at 1/4" thick - definately too flimsy & crumbly. But this stuff - I don't think you can get less than 1/2" thick. I use 1.5" thick for wings & epoxy a fiberglass spar in the top & bottom.
I think I'm rambling now - I need to eat something - & maybe a little Chocolate Thunda!
Chuck is right it is flimsy and crumbly. It isnt as durable as depron. and a wing spar is a necessity. They are hard to get as light as depron. The only advantage that I know of with styrofam is with a hot wire you can actually cut an airfoil wing.
We were doing this a couple or so years back when nimh batteries was the shizznit. This is the only pic I have of a styrofoam plane and it isnt my plane but this was the first electric that I ever saw hover. Its Johns plane. Does it look like a Big ass profile that was at Nashville?