Bespoke Collage Maker

I am after a collage maker which operates within an e-commerce website. (Website design is also required.) The collage maker must offer customers a choice of template i.e. the number of boxes to fill and the background design. It must enable customers to drag and drop photos which automatically fit the space and most importantly allows customers to write paragraphs of text. The end product will be printed as an A2 storyboard and be supplied to the customer in digital format. Customers must be able to play about with the content until they are happy they have everything they wish to see on the printed version so it must be able to be saved as work in progress and be water marked so it can’t be printed without payment. The free online collage makers don't allow enough text (mainly just captions). Once I have the collage maker I will commission the e-commerce site.