The next step in the process was to create the correct shape on the outside of the fiberglass cone. To make my desired pattern to make it look like a shell i used car body filler. I mixed up the filler and hardener (comes as a set from Halfords). I also used a trick i had seen online which is to mix in some fiberglass resin as this makes the filler a better consistency to work with and is easier to create the shell texture i wanted. I used the card provided to apply the filler and i would suggest wearing gloves for this process as it can get quite messy. The filler took a lot longer to dry than in the test i did beforehand but i can only assume this was because it was colder and i had mixed in less hardener. Once the filler is completely dry i spent quite a long time sanding out all the bits of filler i didn't want. You can make it any shape you want and it would be fun to experiment with different shapes. By now your shell should be very strong and if it is like mine you would struggle to break it!