Sewing machine, iron and ruler for the joining. When I get to the point that I need to join the two end together I overlab them, mark (from the end of the one underneath) a point that is the exact same length as the binding is wide, cut the top on at that line, then I just open them up, sew corner to opposite corner (/) trim and voila! Close enough to perfect every time. Then I sew the other side on by hand.