For reference, my bust measurement at the fullest part is 34.5" and I am 5'6".
1. Make these pattern pieces
Some general thoughts if you don't fit into my exact measurements.
A. Make sure the front is a bit bigger than the back, after all, you don't literally want to look like you are wearing a potato sack=) so keep the back semi-fitted.
B. All seam allowances on my dress are 5/8".
C. Make sure you cut the front, back and neck band on the fold line.
D. The front bust width is about 7" larger than my half bust measurement and the back is about 5" larger.
2. Interface the neck bands. I only interfaced half and in return I got a lazy bow. You could try interfacing the whole thing to get a stiffer looking bow ala Ms. Randall herself.
3. Sew the body side seams together and the 2 pieces of the bottom band together. (4 seams total)
4. I then made some 1.5" double folded bias tape with the same fabric and bias bound the armholes.
5. Gather the bottom of the body and sew it to one edge of the bottom band. Then fold the bottom band in half horizontally and stitch-in-the-ditch for a nice finish. A tutorial on stitching in the ditch can be found here.
6. Take a pair of the neck band and sew the top seam together. Do this for the other pair also. Trim the seam allowance after sewing so that it won't look obvious from the right side.
7. Now, gather the front and the back of the body top body seam. Match the right side of the body and right side of the neck band at the neck seam line and sew. Do this for the back piece also. Then turn the neck band over and do another stitch in the ditch to get a clean finish.
8. Cut off loose threads and the likes and then ta da! You have your own knockoff dress!
* Of course if you don't want to make your own pattern pieces you could start from a premade pattern such as one of these! Butterick 5179, Vogue 8229, McCall's 5555.
Just keep in mind that most of these patterns have their necklines drafted way too high for the look. So you'll have to make some modifications there too!