Create a pattern by drawing a diamond that is 4 inches by 3 inches on a piece of paper.

Add an additional half inch to each side for seam allowance.

Cut out your pattern using scissors.

On a piece of similarly-colored fabric, pin your pattern using sewing pins to hold it still on the fabric.

Using fabric scissors, cut out a diamond-shaped piece of fabric following the pattern you created. This is your gusset.