I used a dollhouse wardrobe to make a large dollhouse for a 1/12 scale dollhouse. I added shelves to create the separate floors and added one wall upstairs to divide it into a bedroom and bathroom. Then I made holes in the back wall for installing lights, which are a string of Christmas lights in 1/12 scale.
The next picture shows how the lights were installed. As I only needed 10 lights inside the house, I attached the extra two lights under the house to provide additional lighting for the room in which this dollhouse will be placed. Of course, I could have made two holes for the living room, for example, and installed 4 lights there.
Then I furnished the house. I used pieces of pictures found in magazines for wallpaper and other decorations. The furniture is made of cast metal. Some pieces were ready painted when I bought them, some I have painted myself.