Test Fit a Paper Lining The blue shirt stripe wallpaper in these photos is a free printable wallpaper from this site. I trimmed it and joined 5 sheets together to make a piece long enough to fit the interior of the roombox. Test fit your paper lining, joining several pieces of paper together if necessary to get one strip that will run right around the inside of the box. Begin at the front of the box on one side, and leave at least half an inch of paper sticking out of the front of the box and above the top edges. Smooth the paper over the walls, and use the bone folder, or a scrap piece of book board to form a tight crease in the back corner. Continue across the back to the other corner and set the crease there lightly. Adjust the fit of your paper if necessary.
When you are sure that the paper fits with 1/2 inch sticking out on either side at the front, apply glue to the paper and use the bone folder to smooth it to the walls on the inside of the roombox. Make sure the paper adheres tightly to the edges of any window or door openings.
Set aside to dry
When the paper has dried to the inside of the box, use the bone folder to highlight the edges of the door and window openings (if any) and cut an x across the openings. Fold the paper back through the opening to the outside of the box, being careful to make sure the corners are square
