I am using some fairly irregular shapes, and most of the tutorials I have found have been about baking cubes or rectangular prisms, and I can't get that to work with my shapes, or have been about Blender Render. The objects that I wish to bake are pictured below.
It is supposed to be a building, and there are two rectangular prisms joined to make it. The prisms have been aligned face to face and edge to edge so I know there is no gap or anything between them. The same goes for the door and door frame. The top of the larger of the rectangular prisms has a knife project on it so I can easily remove a section of it and add things on the inside of the building. There is nothing inside it yet as I want to bake it first.
Thanks in advance to anyone who helps, and if there is any information you might need that I have not supplied please tell me.
UPDATE: I tried the solution offered by @pycoder and I got an error saying that there is no active image found in one of my materials. Is this something that is required for baking?