I copy stuff like trees, clouds, and nature things for rendering. God has not sued me yet :o) I say the best thing to do is just get creative and make your own ideas happen. There is no rule that says Star Wars is the best thing to ever happen :o) Another thing is if it's supposedly free stuff and says for non-commercial use only..pass it on by for something that can be used both ways..After all that sort of dampens the whole free theory anyhow, yes?