I got out my paper (printed A4 card paper) harad theme buildings, which I based on the pictures in the Harad sourcebook. Keeping it portable - so that the walls fold flat, and the roof is taped into it, is not very stable, especially with metal miniatures. The roof starts to sag, and it just doesn't work as well as I had hoped. But I don't want to glue the roofs into position, because the whole idea of paper scenery is to fold it flat and stick it in a drawer when not using it.
I got some foamboard off my brother a while back, and had forgotten about it - but I saw it today and had some inspiration.
Here's how to get a stable building, with solid roof, that can be folded up and packed away, using printable thick (card) paper and some foamboard, and some toothpicks :)
Cut out foamboard to the shape of the roof pieces.