UPDATE (March 2016):
I found a way to make it. See the results of my labor here:
Custom leather bound: The Darkness that Comes Before.
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I dream of one day having made a set of Prince of Nothing books with custom leather bindings, like what Franklin Library used to make. The artwork that is found on the original print covers of PoN, or that is found before the Appendix in each book, would make an incredible cover. There are 3 unique pages, TJE and WLW use the same one as TTT (otherwise I'd want to do all of them).
Unfortunately I don't know if there is anywhere that one might acquire such services.
This site:
http://www.bessenberg.com/economy-leather-binding.html , seems like it might be able to, but I haven't bothered contacting them. Regardless, even if they could, I imagine the cost would be astronomical. The unique scroll work/calligraphy and all the "Earwa" text would have to be made as individual stamps, and the detail is pretty high. Even if some of the detail is reduced, its still a lot of custom design and work, so I'll probably never be able to afford it.
But, alas, a man can dream.
For the back cover, at least for TDTCB, I'd probably put Akka's map, not sure about the other two.
If anyone knows of a place that could do something like that, I'd pay handsomely for such a service.