The idea that metadata, particularly Dublin Core, could be usable as a Lego™-like construction kit has been a popular suggestion for over a decade. In this paper, we first explore what this metaphor originally meant – why the idea is so appealing, and what design lessons we might take from the idea. We take a look at how close we are today to that ideal, looking at examples of real-world metadata design projects, and suggest that at present the situation is often more analogous to a game of Tetris – that is, the construction kit is sometimes limited, time concerns are often an issue, and there is limited opportunity for creativity. We explore patterns of collaboration in existing projects, such as the Scholarly Works Application Profile development. Finally, we ask how what we know about the process of building a shared understanding and formalisation about a domain can help us come closer to the ideal of Dublin Core as an approachable puzzle-game or construction kit.