Here's how I did the fun hem of Riley's Valentine's Day dress. For how I did the dress, go here.
Cut two strips of fabric, 6 inches tall. Make them just slightly wider than the bottom of your dress. Mine are about 1.5 inches wider.
Fold your strips, right sides together. and pin along one side.
I tried to get a good picture of this next step, but my fabric marker was too light. All you do is freehand draw a wave pattern. You'll see what mine looks like in a few steps.
Cut out the wave. As you're cutting, move the pins to hold the wavy parts together.
Here's what it looks like. Now stitch along your wave. You may have to put your needle down and lift the presser foot to get around some parts. Since the wave is random, this is pretty forgiving! Yay!
Clip the tops and make little slits in the "valleys."
Then turn it right side out and press...
... then top stitch along the wave.
Now you'll pin the wave to the bottom of the dress, so all the raw edges are lined up. I wanted mine to start and stop off-centered like this.
Pin all the way around, overlapping the beginning and the end. Sew and zig-zag stitch to finish off the edge.
Press your finished edge up toward the top of your dress.
Then (oops! no pic) top stitch close to your seam, on the main dress. You'll catch that finished edge, you know, to show it who's boss.
Ta-da! A super fun addition to your little dress!