For more information on creating custom layouts within books, click here.
Custom Dust Jacket:
Currently this option is only available in legacy hardcover projects - projects started before June 20th, 2018. If your project was started after June 20th, there is no way to create a custom layout in the project.
To design custom layouts for the hardcover dust jackets, you’ll need to reference the document sizes below and create your file so that the spine size of your book is in the center of the document size. From there, account for the front and back image size. There will be .3" on the outer area of both the back and front images that wrap around the edge of the book with the flaps. Within the editor, you will need to add an image and make it the full document size. Then center it before placing your dust jacket JPEG into place.
Lastly, before exporting, make sure you check the “Use Document Bleed Settings” box on export.
Below is an example of how a Dust Jacket file should be laid out. Please note that the exact measurements are not applicable, but the image can be used for reference on how to format the trim zone, spine format and wrap around cover boards.