A clamshell box is a protective box with a hinged lid connected to its base. Both the lid and bottom sections of the box have three fixed side sections. The lid is slightly larger than so that the side pieces ‘nest’ when the case is closed. The fourth spine side has a hinge to join the top and bottom of the box: the flexible joint allows the box to lay flat when opened. Its interior may be lined with paper or suedel, especially if made for a book.