Things you need:
1. Small piece of fabric as long as your doll, and wide enough to wrap around the doll over the bust.
2. A piece of ribbon, jute, hemp, or strip of matching fabric for tying the dress around the neck.
3. Sewing machine with coordinating thread.
Second photo shows fabric wrapped around Barbie and as long as her underarm to her toes. My finger is pointing to the edge of the fabric (overlap about 1/2").
Step 1: Make a Pattern (you Can Use This Again.)
To make this pattern you will need newspaper and scissors. It is easier to do trial and error with the newpaper instead of the fabric so use this method.
To make pattern you will need to cut a piece of newspaper the same size as your fabric. Your fabric and pattern will be longer than it is wide. Fold this across the narrow end to make a double layer of newspaper. You will cut both armholes at the same time so they will match.
Cut this basic shape (See picture) using the following measurements. The narrow top section should be 1.5 times the width of Barbie at the bust line. The underarm cuts need to be deeper than you want them to fall on the doll (almost to the waist). Mine are a little shallow in this picture. You can see where I folded the narrow section because I will fold it over later to sew a casing for the string.
Once you have cut your pattern, fold over the narrow section about 1/2 inch and then scrunch it to look like it is gathered. Lay this on barbie above the bust and wrap sides around to see how the underarm section lays. As long as the paper does not interfere with arm movement, it is low enough. If you want a little more room, just trim it.
Now, smooth pattern out flat again.
Step 2: Cutting Fabric and Sewing Top
Fold pattern in half as well as your fabric. Lay your pattern on top of the fabric and then cut out the matching armhole. You can see the fabric and pattern are the same. :)
You can now fold over the narrow part of the fabric about 1/2 inch, and sew it down. Sew close to the edge but not too close. You do NOT want the stitching to pull out.
Now you need your piece of tying accessory. I really enjoyed working with hemp because it was easy to insert through the casing. You could also use embroidery floss with a needle to pass it through the casing because it is a really short distance. You can choose whatever goes best with the fabric.
I used about 8 inches of hemp. Pass the tie through the casing and leave the ends loose to tie around the dolls neck.
Step 3: Stitching Up and Hemming the Dress.
Fold dress in half, wrong side out. Sew the edges together. You will have a tube with the casing and hemp at the top.
Fold up bottom of tube about 1/2 inch. Sew this to finish the bottom edge.
Pull the dress up from the bottom, tie hemp around Barbie's neck.
Pull dress down snugly to fit Barbie.
If the dress is too lose, you can pull the seam in the back and sew it tighter. However, remember that you need to have room for it to fit over the posterior of Barbie. YOu can also tie something around the middle to add definition to the dress. My daughter used a ponytail elastic. It looked great!