I did a combination between a flag/accordian and a piano hinge book. The steps are pretty easy!
1) Cover your two ends of book board
2) Take a longer piece of paper that is the same height as your text block and fold it back and forth like and accordian or fan.
3) I would recommend gluing your pages in first so that you know the width that your text block is going to be before you do the binding. You can glue them in after doing the rest of the book but you risk the covers springing back.
4) Glue in text block to the front and back cover. Make sure that the text block lines up nicely with the edge of the board.
1) You can use book cloth or leather. Cut out a good amount of your binding material (book cloth or leather) at least three inches wide. I cut out more just because then you are sure that you can make your binding wide enough for your text block.
2) Draw an inch on both ends (or however much you want to be on the covers) and at least 1/2 inch from the head and tail.
3) Now you need to determine how many hinges you want in your binding. However much you want I would draw out the appropriate measurements. This might help:
4) There are specific flaps that help cover edges.
5) So each piece will look like this:
6) Glue the long #2s around a dowel or some kind of rod. Make sure not to glue it to the rod otherwise you will not be able to remove it later.
Hopefully it will turn out something like this or even better!