To catch a sweet ride, surfers rely heavily on two things: the waves, and their board. Surfers can order surfboards that are customised to their needs, or choose from a range of pre-made boards, with little difference in cost. When it comes to surfboard fins, however, it's a different story. Fins are aerodynamic foils that act like rudders while surfing, usually attached to the rear bottom of the surfboard. Fins were once permanently glassed into the board, but these days almost all boards have a removable fin system. Manufacturers of removable fin systems make exceptional products, but the current manufacturing process involves injection moulding, which is very expensive. This pushes it out of economic reach for most surfers looking for a customised fin. Enter three dimensional (3D) printing. We have developed, designed and 3D printed surfboard fins made from composite materials, and have built and trialled prototype fins with flexibility similar to those available in shops.