The Pandora Boxes are cool.. they're made of heavy diecast material. A set of bronze cloth pandora boxes will weighs around 1.5 - 2 kgs...
The strap on the pandora boxes are made from skinlike material. In the anime, seiya and friends often carry their cloth in the pandora box.. it's like a back pack to store saint cloth.
IMHO, they're beautiful but not so accurate with the anime and they're not licensed from bandai. That's why they're called dream box. Still, if you like to have a nice additions in your myth cloth display, then you should have them.
Currently there are three different manufacturers that produce the dream boxes. As far as I know, bronze cloth, gold, cloth, and hades cloth pandora boxes are already in the market.