To make a perfect swim fin you need to shape them by hand. This way you can feel the shape as your hand and mind shape performance. Then once the shape is developed, we can make a mold, cast the fin and go water test. The original Force Fin took over 20 different shapes and 16 years to create. Other fin designer’s use a computer and then go to market with a basic shape used for the past 60 years. This method does not allow you to make many changes to the shape. The process is similar to shaping a surf board.