Thanks for your order on Fantastapack! 😊
For every customized item in your order, you can only upload one file.
If you have ordered a box with two-sided printing, you will receive a two-page dieline pdf. Make sure you have the latest version of Adobe Illustrator (22.1 or higher) in order to open both pages in one document. Once you've applied your artwork, it must be uploaded as a single PDF document, with page 1 being the outside of your box and page 2, the inside.
For more information about how to format a two-sided print file, please read our article "How to format & submit a 2-sided print file".
Take a look at this useful page for more helpful tips with step-by-step pictures!