Oops sorry for the LATE answer!! I just found your comment!
Its different because it gets dry (with air) so so so fast! you have to work with it fast. And when the model its dry, you can leave it ouside etc because water can cause damage .... But the pro is that Cold Porcelain is VERY cheap! And it can be made homade (but its easier to buy it)
This is *EXACTLY* the sort of thing I've been DREAMING of for my new house!!! I doubt I'll be much good at recreating something like that, but I'll be looking out for the perfect boxes, starting this second!
Its not that hard! If i did it ... hahaha Hope you can find the boxes soon!!!