... Is very gold

Let me explain what's going on here:
a)    This is the front skirt. At least, the thin wedge is. The stretched hexagon it's attached to is the ruched waistband
b)    Lining for the ruched front
c)    Back skirt
d)    Ruched front
e)    Unruched front
f )    Back

Everything is angled for bias, which gets a bit awkward once you've corrupted a pattern so much the grainline is more of a grain-angle.

The semi-circle is only there as a guide for the moment. I had done a test layout of the circles and estimated that they might take 8m which suddenly made my generous 10m of chiffon look positively constricting. The line across the fabric is marking out the 2m point so I didn't go much past it. My estimate ended up being exaggerated, so fear not, I didn't run out of fabric at this time.

I sewed the dress together before cutting the circle just in case something went wrong and I needed to re-cut a piece or two, because, if I really needed to, I could probably manage with slightly less than 2.5 circles in the skirt.

The back and unruched front pieces serve as a kind of foundation, and the other pieces are sewn onto them rather than meeting at seam allowances. I found the mere thought of trying to chalk this fabric distressing, so decided to try basting my guideline instead. This worked wonderfully and is a technique I will absolutely be using on future projects. I sewed through my paper patterns and fabric pieces on the marked lines with long stitches and then cut the stitches so I could remove the paper while leaving the thread in the fabric.

Here is the ruching sewn to the lining with tacking to show where that should meet the other front.

Figuring out the sewing order was a puzzle in its own right. The back top and back skirt went together fine – this seam is hidden under the ruching. To join the fronts, I bound the edge of the unruched side and placed it over the ruching. I then hand-sewed them together, with a row of stitches on each edge of the binding. It seemed easier and neater than trying to control it through the machine.

The next step was the long side seam on the skirt. I finished the edges of the waist ruching with Hong Kong binding so it was ready to be draped into place. The front skirt has a small slit in the seam allowance so it can fold out of the seam once it reaches the ruching. The unruched bodice also goes in this seam.

Pause again for another interlude of handsewing to attach the waist ruching. This time the easiest way was on the dressform. Then, finally, the second side seam could be sewn.

Then I cut and sewed the 5 semi-circles and embarked on handsewing the roughly 13m of rolled hem.