All you do is grab some thin elastic that matches your shirt. I am only using white so that you can see it better. Flip your shirt inside out and pin it to the top of your sleeve. Eyeball it to make sure it is in the center of the top of the sleeve like this.
Start sewing just a little and the top of the elastic.
Then pull the elastic so it is stretched out. You are going to have to hold the elastic and the top of the shirt as it's going through so that it will sew a straight line.
When you get to the bottom of the elastic cut the thread and let go and it will bounce up. Do the same thing to the other side and you are done.
Once you are done flip it right side out and it will look like this.
|It's hard to see by this picture but I also did the exact same thing to the sides of the shirt on the bottom. Sometimes quick simple things make a big difference.|