I think it weighs about 1.3 poinds per cubic foot. this is slightly heavier than the lightest beaded eps foam. It is still breakable, however, but much less so than other foams or balsa wood. I have never seen a "normal" looking airplane made from this. (by "normal" I mean with a conventional fuselage and wing). Many flying wings are made from this material, as it works very well in this application. If a flying wing hits hard enough, even this material will break. Also, it must be heavier than balsa wood construction, although I have never made a flying wing in the conventional (balsa) way.