In the book The Works of Satoshi Kamiya, there is a very cute model of an eagle ray with a short tail which is nicely diagrammed. However, there is included in the book the crease pattern for a long tailed version of the eagle ray. Author Satoshi Kamiya left solving the crease pattern as an exercise for the reader. Since I have very little experience solving crease patterns, this was a great opportunity to bridge the gap between diagrams and crease patterns. I could use the crease pattern for the long tailed eagle ray and the diagrams from the short tailed eagle ray and interpolate the new sequence of folds. Additionally, this served as an exercise in modifying an existing model. All in all, this model was the best lesson in origami design I have yet learned!
Folded from a black/black double tissue 13.8" square. I had to fold the short tailed version first to get a sense for the sequence of folds and their effect on the final model. After I was satisfied with the result, I tried to modify the original folding sequence to produce the longer tail. This process went by pretty quickly, as it only took me 4 tries to get it right.