Hall of Justice Concept Artwork
Here we see a piece of conceptual artwork for the Hall of Justice. I have two hypotheses to explain this piece. First, it is plausible that the Hall of Justice playset was first envisioned as a strict carrying case. The wood model shown here further supports this. A second explanation is the proposal of a carrying case in addition to a playset. It is difficult to say for sure, but I prefer the first hypothesis based on the conceptual nature of the art.
Above you can see a close-up of the artwork. The detail on this piece is superb. This art originated from the large find of SP art showcased in Tomart's Action Figure Digest Issues 87 and 88.