One of the trends I've seen in ballgowns lately is that of having the dress being fitted over the hips and tops of the thighs, and then getting much more full at the bottom.

I started out by finding a dress pattern that had a bodice that I liked, which was also a fitted "sheath" style. I used Style (Simplicity) 9218. This pattern is designed for woven fabrics. Since I was using stretch fabric, I cut the dress several sizes smaller than what I usually wear. The dress pattern also calls for lining, but I didn't bother with that.

Instead of making the dress full-length, I made it about knee length. I knew I wanted to make an asymetrical curved dropped waist, where the curve started out shallow on one side (about mid-thigh), and sloped upward getting tighter and steeper to the other hip. I put the dress on, and marked with pins about where I wanted the curve to go, taking into account what looked better on my own body.

Next I took the dress off, turned it inside out, and used a dressmaker's curve to draw the curve that had been approximated by the pins. If you don't own a dressmaker's curve, I highly suggest you get one. I find it invaluable for altering patterns. You can find them at any decent sewing store. Anyway, after I drew the curve, I cut it out, cutting through both the front and back layers of the dress simultaneously.

Now for the bottom of the dress. I measured the distance around the curve that I had just cut, and used that to create a circle skirt. This is difficult to explain without a diagram, but think of a doughnut. The inner circle, where the hole is, is where your body goes. The outer circle, the edge of the doughnut, represents the hemline of the skirt. So, I used the circumference of the lower part of the bodice (measured around that curve) as the circumference of the inner circle. Then I added as many inches as was necessary to reach from the high side of the curve to just above my ankles. This became the radius of the outer circle.

I cut out the circle skirt (as two half-circles), stiched them together to form a full circle, and then stitched them to the hemline of the bodice (along that curve).

The last thing I did was put the dress on my fitting dummy, and cut the hemline to hang evenly on all sides.