- 1). Measure the height of the back of the hoodie, from the bottom cuff line to where the hood is sewn on. Use the measurement to determine the midway point on the fabric. This is where the center of the shark fin will be sewn.
- 2). Draw a triangle on a piece of paper with the bottom longest line being two-thirds the size of the height of the hoodie back, and the point of the triangle where the two short ends meet standing above the center of the bottom line. Cut out the template.
- 3). Pin the template to a piece of grey felt and cut along the template to make the first half of the fin. Do the same with the second piece of grey felt.
- 4). Trace the template onto a piece of poster board and cut it out. This is the insert for the fin.
- 5). Place the two felt pieces together and align their edges. Pin them together on the top two edges of the triangle. Don't pin along the long bottom edges as they will be sewn onto the hoodie.
- 6). Cut a piece of thread that is the length of your outstretched arms. Place it on a needle and slide the needle half-way down the thread. Hold the ends of the thread together and tie them in a simple overhand knot. Insert the thread into the bottom piece of felt near the starting edge and pull it through so that the knot is sitting between the two pieces of felt. Insert the thread through the top felt piece and the bottom piece, near where it is coming out of the fabric.
- 7). Sew the short sides of the triangle together by bringing the needle up to the top felt piece and inserting it at an angle down through the top and bottom piece. Pull the thread through in a whip stitch.
- 8). Turn the felt pieces inside out. Place the poster board insert into the felt pieces. Pin the long edges of the fin to the center of the back of the hoodie. Sew the felt onto the hoodie with a sewing machine with a quarter-inch seam allowance.
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