Bricks
Master member
It is called Model Airplane Foam it is a bit like Depron, but the best part is he has a bunch of seconds he sells for .01 cent you just pay shipping. If interested you can read more about it at the link I have attached if you click on the links on the page he explains the differences between the foams.
Foam :: Concrete (modelplanefoam.com)
Foam :: Concrete (modelplanefoam.com)