When choosing filament (the stuff that your fin will be made of) you have several options. We highly suggest that you choose a very tough filament that is either carbon reinforced (Colorfabb XT-CF20 for example) or has some other claim that makes it tough and stiff. You can also use regular plastics like PLA or ABS for your print. The big advantage is that you can choose any color you like. We do recommend that you do some glassing to add stiffness to the fin. We set out to create a fin that can be surfed straight from the printer and we believe that you will be fine with regular PLA or ABS, but still, there might be some f*ck ups in flex patterns/stuff breaking.
– When printing we recommend a 90% infill. Whatever material you chose to use. Our extensive research has shown that this is better than 100% infill, which may sound counter intuitive at first.