Well I have never done a double wedding ring or a single one for that matter but if you trust me I am game. LOL I think Elanore Burns, Quilt in a Day, has a pattern you applique the rings on top by using fussible interfacing and turning it inside out. Then just iron on and zig zag over the edges with clear thread. Maybe an idea to finnish it off that way.
I have a book some where in the mess that has an alternative method too. If I find it I will post the title or maybe some one else knows of it.