Here is the template for my accordion. It's a little work to make, but makes a nice model.
Just a couple of notes for building.
-The handles you can either glue to the white spots on the end of the accordion or cut the white squares out and glue it inside like I did.
-When building the handles glue the bottom three squares down first to the side with the faces, not edges, giving a little easier making of the handles.
-The middle is just folding, the zig-zag lines are all mountain folds while the vertical lines change. The longer ones are valley folds while the short ones are mountain. This makes the middle hold the same shape as the ends. Then just glue the middle to the ends.
There will be a slit shown in the middle of the accordion that may or may not help it bend, I decided to leave out something that connected both parts together. If you want to try gluing both ends together just leave some paper off one end and glue to the other, I'm not sure if it would help or hinder the accordion.
Anyway, have fun making it.
If you have any questions or troubles just ask, and I'd love to see a few completed Accordions here and there.