As far as I know one cannot copyright something such as the light sabre idea. Work out how to make a real one and you can patent the design but even then it's not copyright as it's not a creative work.
Just as another example from the past. No doubt Bell held many patents on the design of the telephone, still there's plenty of them in early movies.
That's a good point Bob, I never thought of it like that..... It was actually my Client that raised the point, obviously not wanting to get into any legal wrangle with Lucas Arts......
Pleased, he will be, hmph.