Most half baths will include a vanity, sink, and toilet, but little room for accessories. Shadow boxes are shelves built into a wall cavity that can add several square feet of storage. Shadow boxes utilize the space between the wall studs (usually 14 ½”) to house anything less than 3 ½” deep.
If the wall is a wet wall, it contains plumbing and will be double thick. Shelving for decorative accessories, nice soap dishes, or toilet paper holders can easily be recessed into a wall.