if you do the backing being brought forward over the top fabric to make binding, it makes mitered corners as you go along.
take one "side" and fold the fabric over to meet the raw edge of the hexagon and over again covering the hex. pin in place. then go to the next side ,fold and fold again, pin. then on to the rest. I did a lot of them for a quilt so i hand stitched them together.
i also made coasters that way and stitched the 'binding' down by machine with a blanket stitch (can use any other stitch you like).