Secret Passage. Hiding the entrance to a utility room behind a moveable bookcase is a terrific idea until you try to find hardware that's up to the challenge. Hidden Door Bookcases are supported by a concealed steel frame that rides on a heavy-duty ball-bearing hinge. According to the maker, the 10-inch-deep bookcase can hold 500 pounds yet swings open with the touch of a finger. Prices start at $1,965 for a 2-foot 8-inch bookcase. Hidden Doors by Design, 866/530-0003, hiddendoorsbydesign.com.