I went on Coolest-Barbie-Cakes to get ideas and just from that designed my own Princess Belle Birthday Cake. I went and bought the Wilton Barbie Cake Mold and made that, then cooled it.
Frosted it with Wilton Icing then colored the fondant and laid it on the cake, then cut a small hole at the top to put the barbie in later. Then took piping gel and added sparkles and designed the swirl on the dress with any metal shinny thing you can find to resemble the jewels.
Then I popped the legs off her Bell doll and wrapped the bottom dress with saran wrap the bottom of her dress so I could keep the original design of Bell. Then put the Barbie of Bell in the cake and fix everything.