The jacket pattern can be a sweatshirt, a lightweight jacket, or you can make your own base. It is easiest to make it if you can rip open the seams and have flat surfaces to do the 'crazy' part. The 'crazy' part is when you put on your material on top of this base. I don't use a ruler but free cut as I go, sometimes using a straight edge. I like lots of different shapes and angles.
With mine I started in a flip and sew method. Once it was all done I embellished it with some gold trim from Joann's. Then sewed up the seams and put binding on the outer edges.
There are no rules ... except use a size larger than you expect.
ali