For my running princess skirt, I started with the brocade underskirt. I borrowed a costume from a friend's child and looked at lots of images online and put together a sketch of the pattern on the fabric. Then I drew it onto the fabric with fabric paint pens. It worked pretty good.
Sketch and center panel
I took the drawing I did before of the edge embroidery and digitized it and ran it through my embroidery machine. The trial stitch below looked pretty good, so I did the edges of all the panels. Lining up the different pieces wasn't as hard as I thought, because the bits of the design do not touch. Approximate line-ups worked here.
I knew I would want a pocket to put my iphone, tissues, hotel key, etc, so I added a waistband to the top and put in a pocket and an invisible zipper.
Finished Skirt, front
Pascal shows off the pocket
(He will not ride in here for the race, he just hopped in for demonstration purposes.)
Finally, I attached the skirt to a pair of white running shorts. The shorts I didn't make because I don't have enough confidence in my seam finishing to know they would be chafe free for 13.1 miles. I did add some white lace to the bottom (ending before it got to the chub rub chafing zone) so it looks like Rapunzel's petticoat peaking out the bottom.
So there is the skirt. Onward and upward to the top!