Thank you for your reply.  How do I combine multiple apps?  I have found 2 apps that can together do what I need but I don't know how to combine them.

I'm creating a shop to sell custom shirts.  I want the user to be able to choose the shirt color, upload their design, and see it change on a mockup picture of a shirt as they do so.  Once they have finalized their shirt color and design I would idea...