I had a Fluttershy base body that needed a serious coolness boost, so I decided to make her into a Spitfire.
I sculpted the hair and goggles out of colored sculpey, gave her a deeper yellow color with a quick coat of acrylic. I painted the hair with sculpey matte glaze to seal it up. the cutie mark was troublesome, but I went with a flaming lightening bolt (it seems like all members of the Wonderbolts have a lightening based mark).
I will have more of these for sale, $30, but I won't likely post them online. You'll have to see me in person at a convention artist alley or NY Brony meetup.