There’s a space in my small hallway that is hollow behind the wall. Basically there’s a cavity between the wall and the chimney—I can see it from the attic. I’d like to add a small linen closet in that space but don’t have much of a budget to do it. What’s the best way to do this? Could I build a wooden box, wrap it in insulation, and just sink it into the wall with a door that’s flush with the wall? It seems like there’s some way to add storage here that isn’t overly complicated but I just don’t know how. Any advice? Honestly just something like this, just sunk into the wall.