Dynamic PDF

Needing website to produce dynamic PDF files that can be downloaded and printed. I need a web page that can display specific templates I have created that user can change the font, color, wording, upload photo etc on the template-- then pay, download file and then print from their personal printer. What it would look like on my site: * a page that displays all of the template choices * they click on a template, which takes them to a page where they can make their changes (font, color, wording etc) * see a proof * approve and save * pay * download the PDF they created * It would be important once they have payed, created and downloaded the file it can no longer be changed! * They would need to login again and create a new PDF