Easiest way would be to buy nice thick-woven fabric for your front layer, and a pre-quilted fabric for the back. They stock them in the quilting section, and you can buy ones that have raw calico on them, this'd be the best for you because you can weather/paint/dye it to match the colouring of your costume.
It's been a while since I've watched that scene, but it looks like four panels? Lets say they overlap by an inch and a half, so measure your waist and divide that by four, and add an inch and a half. And then taper the bottom out so it looks something like this
(red mark is where your 1/4 waist would measure)
Then you'll have to edge it, easiest would be to use bias binding (have a google for a tutorial on how to use it, and remember lots of pins!).
And as far as knotting it goes, use something like an embroidery thread and stitch and tie it at intervals.
And I'm very tired, so I'm sorry if this makes no sense.