The bays need to be finished away from the dollhouse due to their small size, which also makes it easier to work on them without the window mullions in place. Before installing the bays, you must completely finish their interiors, including installing the windows.
I started by priming the interiors of the bays and then painted the mullions. Next, I applied wallpaper to the tops and bottoms of each bay wall. There's no need to worry about the sides since they will be covered by the window trims; just get the wallpaper as close to the top and bottom edges of the windows as possible. You don't need to use a large tub of wallpaper paste for this; in fact, I recommend against it. The paste is thick, and since the bays are very small, using a heavy paste could be excessive. Instead, a little tacky glue applied with a foam brush or even a glue stick will work well for these tiny areas.
While the glue dries, prepare the opening for the bay wall. Since there is no interior trim around this opening, aim for it to blend closely with your wallpaper. I painted the edges blue after sanding them, but you can use any color that complements your wallpaper. I could have wrapped the wallpaper around this opening when I decorated the room, as I did for the Beacon Hill Dollhouse bays, but this dollhouse is so small that it wasn’t worth the extra effort. The edges of this opening are hardly noticeable due to the scale.
This dollhouse does not come with pre-cut windows; you will need to cut them out yourself from sheets of acetate plastic included in the kit. I recommend using your interior window trim as a template for cutting.