Use fusible interfacing. Possibly more than one layer. Fuse all the individual pieces before sewing them up. Topstitching the seam allowances also provides a little more stiffness and helps reinforce the overall shape, if you don't mind that kind of design touch. (I really like the look of narrow topstitching, but other people may not.)
FF9 cosplay? Hit me up!
2014: Anime Los Angeles and whatever else falls into my lap
I now have a Tumblr
. Sometimes I use it.