Here are 3  ways to make the cold shoulder top . 

Method 1

The easiest cold-shouldered top you can make is to refashion a loose top you already own or buy a  top in sale and adapt the sleeve to a cold shoulder style.Check out the details of how to refashion t-shirts like this in the post on t-shirt refashions here

Method 2

This is a long cold shoulder sleeve . You can easily add this to any bodice/ tshirt you have

Make a simple sleeve following the pattern given below

A-J Should be mark according to your bust round or as per your bodice armhole

Attach the sleeve to the bodice armline. Bind the cut edges with bias binding 

Method 3

To make this top cut a pattern for the basic bodice blouse given here in this post. I have decided to make a loose one without waist shaping. You also need two sleeves as per the pattern given above.

Fold fabric pieces for the sleeves and mark the following pattern and cut along C-E-D-A-C.

From the side seams mark 5 inches up on the armhole line and cut the sleeve straight. 

You will get two pieces like this. Bind the top and bottom edge of the sleeve pieces with bias tapes.

Added a panel of denim from an old skirt to the bodice piece 

Hem the top and bottom edges of the sleeve pieces. 

Bias bind the necklines of the front and back bodices. After that join the shoulder seams

Now bias bind the armhole lines

Keep the sleeve piece armhole edge under the bodice armhole edge aligned from the side seams . Stitch in place on both sides

Join the side seams. The top is done