I am not a huge fan of the birthing method but in this case, I think it would be the way to go. You lay the runner face down on top of the backing fabrics that is face up and have the batt on the bottom. Sew all around the edges leaving a small section open the turn right side out. Trim around the edges, turn and then quilt. I think Jenny Doan has a similar design runner but with bigger squares that she birthed on her MSQC youtube videos. OR you could try to put binding on but I don't recommend it in this case.