Thanks!
Yeah, I for one would definitely buy a properly done printed artbook for the Void, it would be awesome.
In any case, I've made a few minor changes to the proto-artbook above:
https://docs.google.com/open?id=0Bx9l0v ... FQ4VTB0MWs
Text colour is now white (it seems less gaudy than the orange did),
Page numbers and a contents page now exist, sections have been re-ordered
I've added quotes in for the 'The Void', 'Doppelganger', 'The Sisters' and 'Death' pages (all of which are from Death's dialogue as I'm still early in the game in this runthrough) and haven't really met anyone else yet (so all are subject to change)
I plan at this point to expand the sections on all the sisters (and probably brothers) with a quote, the relevant poem from the ending, and work their favourite colours into the page somehow (I'm not sure) as well as integrate artwork for each of their chambers (though this may be better of under its own sub section? I don't know).