I have an octagon wallhanging. It was actually a Christmas tree skirt that I completed the circle on. I made a sleeve for a slat with hangers on each end. THose two hangers get a nail. The corners have velcro hand sewed on them. I put a small piece of Command Strip velcro on the wall. I just 'tack'those corners down on the velcro. If you are interested in pictures I can take some for you tomorrow. I am out of town but home tomorrow fairly early. Reply to this thread or PM me and I will post them here. Love your wall hanging!

This was going to be my suggestion as well. Make a couple of little 'pockets' and hand-stitch to the back of your outer-most points and get some small dowel rods at Home Depot or hardware store. Might need to do a secondary frame-set for the smaller outlying points as well.