Oh, I thought you meant for travel when you were talking about your carry-on--like you can do this while rolling through the airport or the convention halls. I didn't realize you were talking filk circles and the like. Now I see.

I thought a little about laminations and reinforcements of various sorts but the reinforcement has to weigh less than the material it's replacing. I don't have a list of weight-versus strength for various things so I'm going seat-of-the-pants type intuition here.

I certainly have the technique down to reinforce with a layer of fiberglass on each side, but that works best with a curved surface, which plywood doesn't provide (and which would be considerably more of an engineering challenge to design and build in a short time.) Also, epoxy is spendy compared to plywood, and in my opinion is best used over a surface nice enough to make it worth your while. (Though I did just have the most amazing idea for an electropunked canoe...)

My constraints here are sturdiness, dimensions, weight, money and time, in roughly that order... If I abandon the notion of checked baggage and think of it as a "travel to and in cons thing" the sturdiness, dimension and weight constraints slacken somewhat... Still have to get it into a car, of course, and it still should survive being stepped on or dropped.