In one sentence, describe what the following article is about:

This simple method ensures the vest will be a good fit without the hassle of measurements, etc. Seam allowance is the part that gets folded under when you make the seams. For each half, fold the t-shirt in half vertically and trace around it, adding seam allowance along the outer edge plus a little extra room for the front-center overlap if desired (e.g., where you'd put snaps or buttons). Again, add room (1/2 inch) for the seam allowance. Keep in mind the back may have a higher neckline than the front pieces, depending on your design. Put the cutout pieces together as they would be for the vest, making sure the armholes and hem line up. You'll need at least 1 to 1 1/2 yards for the vest, and an equal amount for the lining.  The lining is the part that goes inside the vest, on the reverse side of the outer cloth. If you have doubts as to how much fabric you need, take your pattern to the fabric or craft store and ask for help. It's always better to have a bit extra material than not enough. You can choose from a wide range of materials for your vest. Keep in mind the season when selecting your fabric; for example, you can use a light wool for autumn, velvet for winter, seersucker for spring, and silk or light cotton for summer.

Summary:
Trace a tank top or a t-shirt (with sleeves tucked in so you can get the arm openings) onto pieces of newspaper or a brown paper bag that's been opened up. Add about 1/2 inch (about 13 mm) around the entire outline for seam allowance. Make the front piece in two halves. Make the back piece by laying the t-shirt flat and tracing along it. Cut out the pattern pieces and inspect. Buy your cloth.