Usually a kit would provide a piece of bending birch for part #60 where it curves on the beakhead. It is soft and bends easily, but if you soak it in water and place it in a concave form and apply heat with a hot iron, it bends a lot more. Part #60 has two bends in each piece for the beakhead. An electric hot iron can be obtains from Model Expo or Modelers Central. Sometimes you can get away with soaking the part in water for 20 minutes, an carefully pressing it into a form to give it the shape you want, hold it there with a series of clamps, and let it dry, and it will mostly stay in the desired shape. If you don't have bending birch wood, linden can work because it has a small grain and can take bends also.