Minecraft wiki entry for Building_a_metropolis, associated text: Enderman Art Show Put endermen in a room of blocks they can pick up. After a set amount of days, see how they changed it! Players can bet on certain blocks being moved. Make sure that the endermen are kept in a glass cage, though, or players might anger them. Make the room out of bedrock, as Endermen cannot teleport through them, and the glass only 2 blocks high as endermen cannot teleport through blocks that are shorter than them. Also remember that Endermen can despawn over time, unless they are named with a nametag.