Elaboration expands a poem. We can plumpen a poem through a number of devices and methods such as conceit, simultaneity, inner correspondences, slant imagery, creating a story within a story, and correspondence.
Who better to talk about elaboration than Richard Hugo? In this video, he touches upon the importance of elaboration: "The less you know about the town, the more you can add...subtraction is always more difficult than addition." Just listen to him read, "Degrees of Gray in Phillipsburg." Hugo skillfully utilizes the setting as his "triggering town."