The MOO PHP SDK by Jonathan Oddy is an unofficial resource to interact with the API. Resources provide installation and usage. Examples demonstrate authorization with Api Key and Api Secret, in addition a request and a response to create a pack of business cards.
Printful, a drop shipping service for custom print products and a product of the same team who created Startup Vitamins and BeHappy.me, has provided the Printful API that will allow people to easily integrate the functionality with their websites and applications. The service is specifically aimed at small and medium websites that want to offer print products, but don't want to handle the fulfillment and shipping of those products.