This YouTube video is from Printful:
Our generator allows you to create well formatted print files that match our printing guidelines to send through to us.
This makes the fulfillment process smoother, since all the print files you generate match our guidelines and are ready to be printed.
The mockups you create serve two purposes – you can use them as a product photo on your store and they’re also extremely useful to our fulfillment team as a reference when submitted together with a print file.
Find our guidelines for creating print files under each product: http://bit.ly/2ekS4op