It's made out of light-weight upholstery fabric. My daughter takes her little boys out on Hallowe'en and the theme this year was dinosaurs - she likes to dress-up too. I free-hand made the pattern bigger than the ones for the little boys. I left the spikes the same size but just doubled the number. My daughter told me to use up some ugly fabric.
Sorry it's blurry but it's hard to take a photo of one's arm inside the tail while trying to keep the spikes open so I can photograph the accent fabric I used. It's the same as Luc's but in green instead of yellow.