I tested a book pillow of the kind often used to display rare books but it was immediately obvious that it wasn't suitable. I wanted the book to be handled but it just skidded about on the tyvek cover. I found photos of a drop spine or clamshell box with integrated book cradle... a tenuous link between cradle and motherhood book maybe but there you are.
The cradle was made first then the case built around the cradle and book. The cradle is fixed on one side of the case
The finished case both protects and supports the book.
I'm following my bliss.