The updates on the Penguin UK blog are not frequent but always engaging. Check out this entry to reveal, among other things, how a simple sketch like the one above becomes this design concept:
Then interpreted in this manner:
Before all components meld in this proof:
Fascinating to me. Not even that thrilled with the final product, but just enjoy seeing the process. Go read the whole post by Penguin Press art director, Jim Stoddard for insights and more interesting images.