In one aspect, a film assembly is disclosed comprising a first optical film having a tab disposed outside a first viewable area and a second optical film proximate and parallel to the first optical film, the second optical film having a slot formed outside a second viewable area; wherein the tab and slot are arranged to permit the first and second films to be moveably interlocked. In another aspect, an interlock arrangement for an optical film stack having at least a first and second optical film is disclosed comprising a penetrating member formed on the first film and a receiving member formed in the second film, wherein the film stack is moveably interlocked when the penetrating member is moveably secured in the receiving member. In another aspect, a method of assembling optical films is disclosed, the method comprising moveably interlocking two or more optical films to form a film assembly.