Back in the day, most people bound them following the hexagon shapes making tiny tucks on the inside corners and miters on the outside corners. Most people today either cut half hexagons for a straight edge or use a facing binding. A facing binding is where you sew strips of fabric to the quilted quilt edge following all the angles. All the inner corners are clipped almost to the sewing line so it turns to the back well.The facing is them completely pulled to the back like a facing and hand stitched to the backing. If you Google Hexagon or GFG with facing you can probably find a tutorial to follow.