There was a lot of interest in how the neckline was done so you'll find the tutorial below.
On a side note, I'm not sure if it is the "correct" way to go about making this neckline, but it worked for me and the whole project took less than 10 minutes so I'll take my chances :)
Here's what the final product looked like:
Here's the tutorial:
1) Starting at one shoulder, drape your ruler across the neckline to the other shoulder. Place the ruler so that the point of the V shape is where you want the neckline to be the lowest. Remember (or write down) this measurement.
2) Measure the desired length of the dress by measuring from where you want your shoulder strap to lay to the bottom of the dress.
3) Fold your fabric in half, right sides together and cut it. You'll likely be cutting a large rectangle, here are the dimensions:
Top of the rectangle: Your measurements from step 1 plus 3 inches
*if waist/hip measurements are larger than this you should account for that measurement accordingly and the fabric cut will not be a rectangle*
Sides of the Rectangle: Your measurements from step 2
*Make sure you're cutting 2 layers of fabric at these dimensions*
4) Starting at the location of the lowest point of your arm hole (you may want to measure this) sew the two pieces together on the blue lines (see picture below) and trim fabric closer to seams.
*since the fabric had a stretch to it, I used a zig-zag stitch*
5) Using your measurements from step 1 (the distance from shoulder to shoulder including the plunge of the neckline) mark where the shoulder straps will be made.
To do this, measure 1.5 inches in from each side (and 1.5 inches down from the top) and mark a dot. This dot will be the center of your shoulder strap.
6) Sew the top corners of the dress together, using the dot marked in step 5 as the center of your seam, sew at a 45 degree angle to form your straps, as seen in the diagram below (marked with green) and trim close to seams
7) Turn fabric right side out, taking each shoulder strap separately either pleat or gather the fabric and tack it in place (this helps encourage some of the fall of the fabric along the neckline)
8) Tie a piece of scrap fabric or some sort of a belt around the waist area and you're done!
*When the cover up is not actually being worn, the shape of it looks pretty crazy as seen below. The top looks really wide, but that's because it's laying straight across, not in the V shape*
Here is what is looks like when the shoulder straps are in place and everything falls the way it should.