I made my first double wedding ring last year; I used the paper piecing; it was awesome and everything fit perfectly. Here I a youtube link too, to Shari Jorgenen's video on how to make one using her templates. I did not use hers but she has some extremely good suggestions on the procedure; the one video on how to actually assemble it was most helpful. She also has a video on how to bind it.
https://www.youtube.com/watch?v=eQPmfGp8wmQ