There used to be "ultralight MDF", but I haven't seen it around for quite a while. I think it was using pine or basswood. It was particularly poor at holding fasteners.
Jason Holtz J. Holtz Furniture
3307 Snelling Ave. South
Minneapolis, MN 55406 612 432-2765
-- Jason J. Holtz Furniture 3307 Snelling Ave. South Minneapolis, MN 55406
Jason Holtz