Just like with the ceiling, I made a template of all three walls using copy paper. These walls are simple enough to be able to do this with copy paper but if you have more intricate, oddly shaped rooms you can do these templates using index cards. The index cards are small enough to allow you more flexibility when going around windows and doors. This is especially true if you have trim around the windows and doors. This dollhouse does not, so I was able to just crease the copy paper over the window in order to transfer its shape.
Don't worry about the corner joints. They will be covered with moldings. When you are using templates for finishes, you will always have to use interior corner trim.
I then transferred these copy paper templates to poster board. I dry fitted the poster board templates, to ensure their fit.
Then I applied the wallpaper to each of them. I used Mod Podge, just like with the ceiling. If you need to join wallpaper together, in order to make the length of the room, always have the seam face away from you. Make sure that you match the pattern, so it continues through the joined seam. I had to join the long wall because scrapbook paper is just not large enough to cover it with one sheet. In this case it was unavoidable but normally, you will want to avoid having to join wallpaper in this way, especially when using templates. Since you are adhering paper to paper, having to apply a third paper layer, can make the template very wet, causing wrinkling. I had some bubbling and wrinkling at my overlapped joint but thankfully, it flattened out as it dried.
While your template is drying, keep it laying flat. If you allow it to curl, you will get wrinkling when you try to flatten it out later. This is about the only time that Mod Podge quick drying time will be to your benefit. The faster your template dries, the less possibility of it wrinkling or warping when lifted in vertically. It literally just takes minutes for you to be able to handle your template safely.
I glued the finished templates to the wall. Make sure you do a dry run, in case you need to tweak the fit. Remember, you will not be glueing these permanently to the walls if you have wiring in place for your dollhouse. Just like with wallpapering, you want to apply the far, front wall template first and then the sides.
I began to add moldings around the ceiling with some extra, already painted trim, I had on hand. I also started to create the door frame but I will finish the moldings at the end. You can see how the dollhouse is starting to come together on the interior.
