The exterior walls on my home are extra thick, so the window ledge is quite wide (6 in). I cut a piece of hardboard to fit. Half is painted and flocked to look like grass. The other half is painted like a cobblestone street. The backdrop is a scrap of painted canvas from my diorama shelf (something deserving of its own post). I also have a foam brick wall from a model train store. That is used with the cobblestone floor for an urban setting (as seen in my Town Guard post).
I realize not everyone will have a good window for this type of miniature photo studio, but I think it's a clever little set up. Most of the close-ups of models on this blog have been photographed here.