I've done origami workshops at conventions before. In fact I'm down to do one at Year of the Teledu. I restocked on paper at the Japanese Shop in Chester during Eastercon, and I've been folding again.
Those models are all folded from squares about two inches on a side, which means they're mostly between a quarter and a half an inch across (say six to twelve mm in the new money).
Questions: Is it worth me putting something together for the Novacon art show? Is it at all likely that anyone would want to bid, on something that I'd routinely give away free in the bar anyway? Should I attempt something particularly complex for the show?