Anna's Hummingbird - 3D Lenticular Postcard - Greeting card 3D Postcard of an Anna's Hummingbird 4"x6" postcard - comes in a protective sleeve back of postcard has lines for mailing address, along with a Hummingbird's size compared to that of Man and a map of its habitat All flat 2D photography is just a poor attempt to emulate natural perception - as we see things with our two eyes. 3D images are more natural and more enjoyable to view.