I meant to post some pictures about my hard covered books,
showing the covers before attachment. So here ya go:
This picture above is of the covers finished but not attached to a book block.
This shows one of the covers "inside" before additional support is added to the spine. My favorite additional support is tyvek. But you could add a nice washi paper of any paper really and glue it in along the spine. Then glue in teh book block.