This was the most fun, most difficult costume I made. I made the Sunny costume a bit big hoping she can wear it again next year. It was made from 3 different patters and a lot of custom work.
The fabric is a gray faux silk, I liked the texture. I also bought a sheer lavender and zipper. The rest are things I had laying about the house. Some of the images in the movie make the sleeve color lavender and others pink. Make your choice.
Use the same style sleeves from your Rapunzel pattern. Or princess/colonial or 80s style dress.
The yoke is from a vintage sailor pattern like this one, look through your old patterns like I did and modify something similar and add it to the Rapunzel sleeve. Or buy one, like the one sold here. I used the sheer to overlay the gray on the collar as well as added black ribbon to the boarder.
In order to have the ribbon arm bands stay in place I inserted a 1″fully lined strip (the same fabric as dress) to the underside of the sleeve and attached the ribbon to it evenly. The “buckle” is a trimmed piece of stiff felt. Next time I would affix Velcro to keep them tight on the arm, the ribbon slid out of my make shift buckle too many times for my fancy.
The tie is a knot of 1″ grosgrain black ribbon I hand stitched in place. If your pattern includes the ties (as mine did not) all the better for you.