Diorama Infinity lets you create infinite worlds inside your Echo Show - by turning the Show into an augmented reality diorama creation platform. You can either use this skill by itself to view safari diorama screenshots created by other users. Or, you can create your own by downloading the iOS app.
Every time you say "Alexa, open DIORAMA INFINITY", you get a random screen that a user created. Point your phone or tablet (once you grab the app below) at the screen to "see into this world". Note that as you move your device, you can see so much more than just the plane of the screen - it's an entire infinite space!
If you want to create your own diorama, simply summon a Grid. Say: Alexa, open DIORAMA INFINITY and load a grid. The creator menu shows up. You can now sign your name. The upload button also appears when you are ready to upload.