stable angular separation the nature of the interconnection of the pages at the spine edge is adapted to suit the material of the pages and may include stitching or springs it will be further appreciated that the interconnection of the pages at the spine edges also contributes to the self supporting nature of the book in the open configuration providing resistance to the pages falling against one another in further embodiments composite construction may be used such as trimmings on the pages to give resilient soft or furry external edges some trimmings maybe incorporated in a sandwich structure with the pages stiffeners such as card or ribs may be included within pages of less rigid material other structures that may be included within the pages of metamorphic books include holes in various parts of the book through which a finger puppet or length of wool or ribbon for example can be inserted pages may also have flaps that can be lifted such flaps either having cuts extending through both sides of the page so that the same flap can be pushed or lifted from both sides of the page or alternatively a flap maybe provided on just one side of a page flaps may be interlinked or extended to create pop up structures an important feature in giving sufficient ruggedness to the structure is the thickness of the pages and the resulting width of the spine of the book it.