I've lived in a Residence Hall on campus at my University for the last 6 years. Our heating/air conditioning units aren't very decorative, so to spruce things up, Adam made me a mantle to go on my unit my third year on campus. This past Christmas, Dad had his cousin make us a fireplace to go with our mantle! (She owns a sign business making vinyl signs and decals.) For our fireplace, the put the vinyl on a huge magnet.
(This is actually the unit in the den/kitchen, but they look the same..this one is just a little longer.)
Ta-da! The magnetic fireplace stays on the metal unit and the mantle just rests on top of the unit.
...oh, and we seem to have lost one of our vents during moving :/
But...he got those plastic air redirectors that you put on floor vents to make the air come towards the room so that the air would redirect out of the mantle instead of just cooling off the top of the mantle.