Free! will be having a Creation Notebook that will include five categories: Staff Illustrations, Prototypes (layouts of earlier designs), Episode (interviews), Animation Works (of the entire series), as well as Special (free-form depending on the volume).

It seems like the commentary will be recorded, so perhaps this will come with a CD? 

There will be Five Volumes, with the first Volume’s reservation period starting from August 24th to September 7th! I will be taking pre-orders on my Storenvy as soon as the price for this is released!