Sewing with elastic thread is so much fun! I did it recently with the side gathered shirt and then again here today.
This shirt was really easy. I put elastic thread in the bobbin and blue thread in the needle. I just sewed in loops and triangles all along the neckline. Next, I cut off the sleeves and hemmed the holes to make a tank. I cut 4 circles of different sizes and sewed them on top of each other into a flower, which I sewed to one shoulder.
That's it! Just buy as shirt one size up to allow for shrinking at the gathers :)