It's a fairly symbolic building, looking rather more like a cave, but it has a "roof" and an interior which can hold a few chairs and a small table, or other limited amount of bits and pieces. In practice, the lack of realism doesn't matter, and it works well. We've used it as a house, and as the stable in Bethlehem. Here's a picture from the 2006 Carol service :
and here's another from the 2009 Carol service :
The major structure is the building's "facade", which is constructed from two collapsible clothes driers, each designed to open into a quarter-circle, and joined together to form a semicircle :
|Drier closed :|
|Drier bent :|
|House frame :|
The wooden structure is held in this position by additional wooden struts. It is draped with cloth, usually leaving the front open. The back has usually been extended by spreading the cloth over ( say ) chairs, thus providing a closed space, and allowing space for furniture if necessary.
We used the building in at least these services :