I made my youngest girl one the same way a couple of years ago.
I took one yard of fabric of two fabrics. Pre-washed and dried them both. Curved the corners with a bowl, sewed them together, added Velcro straps decorated with a button to finish it off. I found the dinosaur fabric at Joann's. If you want to make your own and need step by step instructions, just do a google search and a bunch of free tutorials will come to your rescue :) Just pick your favorite one to follow.