If the metal isn't stretched and there are no hard creases in it, a suction cup may work. A few people have had luck with a plain old bathroom plunger. Wipe any dirt off the roof and wet down the edges of the plunger for better adhesion. Work from the edges to the middle. BE GENTLE when applying and removing.
Other people get suction cups from harbor freight that lie flat on the surface - then you create suction by pulling back on a handle in the middle of the cup. Same principle is used to handle plate glass, car windshields and even raised computer floors... so you might be able to borrow a suction cup from one of those businesses.
Also plain old sunlight can cause the dish in to pop back out.
Today is a gift, that's why they call it the present.