This is an R/C airplane, specifically a "Viper Twin". I don't really know further details, but it's about 4 feet across, and made of a material that's similar to styrofoam packing material - only much tougher.

We weren't sure how well the paint would adhere, so it's just a quickie freehand design. Apparently though, it's holding up quite well.
(despite, as I'm told, a nasty crash - nothing some epoxy can't fix though)