I made one for a friend to give to her granddaughter - fussy cutting a square around each princess then just put sashing around the block. Sorry I don't have a pic... thought I did but can't find it. If you are wanting to cut around each princess, I assume you are planning to applique them onto another fabric? I would still put sashing around that block. It turns out nice.
Adding this thought - for the "sashing" you could make little blocks of the different colors in the dresses and sew them together. Kinda like a cottage quilt sashing. Hope you can understand what I am trying to say ;-)