I am pretty open minded about this, However I would really like it to be something mechanical, or it could be modeled off of something in a movie, like, back to the future delorian, explorers, tilt a wheel. ect... But I think if it was based off something in a movie, that both people should be modelin the same thing. if whoever is wanting to challenge wants it to be more than a week depending on the complexity of the competition, than that is perfectly fine with me.
Brian