It's simply an empire-waisted dress of white cotton, fully lined. The bodice is darted, with a thin 'waistband' that joins to a rather full A line skirt. The sleeves are removable, as they are sewn onto a separate cotton underbodice she can wear with the dress or not. The sleeves are made of polyester (non shiny!) chiffon. It closes with an invisible zipper in the back. All materials were from Hobby Lobby.
Here you get a better idea of the sleeves. Large triangle folded, with seam along underarm, sewn together until the elbow, then left open. Hemmed with baby hems using extremely thin strips of sew on interfacing, all straight seams.
I sewed the sleeves onto a removable bodice she could wear underneath the dress, here you see it slipping out a little, I'm going to put stay straps in place.
She's so pretty. She made the necklace herself, from jump rings and home-made baked dough, painted with metallic model paint. She also made the belt herself, from painted fabric, cardboard, and buttons.
UPDATE: Jenny's R2D2 DRESS!