Hmmm, good ideas. After I posted I also thought about encasing a wire between two lengths of fabric or ribbon. The wire would allow it to be rigid enough to stand away a bit, but at that length it would also be "floppy" enough to flow like a feather.
Next question: This year I am making Amestrian military uniforms, and I can't for the life of me figure out how they get into their pants. The pants clearly have a front fly (zipper fly?), which doesn't seem to extend up into the waistband, indicating that the white waistband thing is a separate piece. I have screenshots of it being used to suspend belt pouches in the absence of the "skirt" (FMA:B episode 14), so it's definitely supposed to be an independent piece. I think it's a belt with two buttons in front that goes over the "skirt" and pants. But the belt doesn't seem to have a closure or seam in back, side, or front, or underneath either of the buttons. Moreover, when Hawkeye, Ross, etc. need to attach things at the waist (like guns), they use a separate brown partial belt that hooks onto the front buttons, indicating that either the standard white belt might not be up to the job, or that they put these things on after they get to work. Hughes' white belt houses his throwing knife in the back so I'm guessing not the back. Nor does it seem to be attached to the pants in any visible way. If it's not attached at all, this means (a) it's not serving to hold the pants up and (B ) it'll displace itself quite easily, especially at center back where the pants waistband lowers when you sit down. My vote is for "attached invisibly" then-- but how? Inner buttons? hook-and-eyes?
I did figure out how Ed gets into his pants though. Ed's pants actually have a wide brown (leather?) waistband with a front opening but no closure (you can see this when they strip him in Rush Valley to examine his automail). The pants are held together at the waist by a matching brown (leather?) belt that goes through the belt loops attached to the waistband. That would make sense from a garment care standpoint only if his pants were also made of leather, which in turn makes sense because I bet automail wears right through ordinary fabric pants.