I decided to make a change to the books by backing the copper covers with painted grungeboard for extra stability.
I used a strong adhesive, putting it on the grungeboard and the back of the copper cover.I pinched the copper to the grungeboard all around the edges to make a good bond.
To finish the covers, I used a paper stump to wrap any extending metal edges around the grungeboard and also to help make a strong bond between the copper and the grungeboard.