I made my guess in the project's blog... and failed :)
Anything else you think it looks like?
Hester emailed to say: Today's envelope reminds me of an airport terminal map.
Ideas from my household include seating chart, game, pill, corn, button hole attachment...we'll keep thinking!
martian cribbage board
Great guesses, everyone!
Looks kind of like a football field, but stamps make me think of food. One of those tray thingies that holds an ear of corn? A zipper?
All will soon be revealed.