The Artgame 3D bookmarks are lenticular and tilting it back and forth gives it a 3D effect or shows another image. They are 6 x 2.25 inches (152 x 57 mm) in size. They also come with a tassle or a soft-plastic token to help find your bookmark when in use.
This Star Wars bookmark shows an alternating image of Rey and Kylo Ren with their lightsabers...spoiler alert! Comes with a Kylo Ren marker.