Find an 11 x 17 inch piece of paper to make a book dust jacket. For most books, this paper size is adequate.
Center your book in the middle of paper. Locate the spine's edges. Draw vertical lines on the paper from the spine's edges to the top and bottom of the paper. Remove the book and cut along your markings. The result should look like rectangular spine flaps.
Fold in the book spine flaps inwards.
Align the book on top of the folded spine flaps. Open the book. Fold the remaining portions of the cut top and bottom flaps over the book's cover at the top and bottom.
Loosely wrap the remaining, unfolded paper over the left and right sides of the book's cover. Hold the loose folds and close the book. You will find that the book needs extra space (usually about one inch) between the book's cover and the dust jacket to close properly. Use the loose folds to find out how much space you need for your particular book. When you have found a snug fit, turn the loose folds into proper folds.
Cut sheets of paper of about the approximate size of your book's cover. Insert them in between the folds of the book dust jacket. When you open your book, it should look like the inner and outer book covers are completely protected.
Glue the book jacket folds and the inserted sheets using drops of PVA cement or non-acidic glue.
Put scraps of paper between the folded jacket area and the first page of your book to prevent the PVA cement or glue from staining or sticking to your book.
Decorate the outside of your book dust jacket. You may use stickers, glue photographic prints or draw with markers that do not smudge. Personalize your book dust jacket to identify the book and claim it as your own.