Okay, cut four long pieces of fabric about four inches wide. Measure them so they match the outside four inches of the quilt. Now sew them together so they look like a picture frame, but are the size of the quilt, not bigger. Put the quilt and this facing right sides together. Stitch from the quilt side in a 1/4" seam, following the outline of the hexagons. Clip corners as needed, turn the facing to the back, press well, then handsew the loose edge of the facing to the back of the quilt, turning the edge under as you go.
Works best with table runners and wallhangings, but it could be used if you are determined not to bind the edge.