Thanks for the answer Alexander. I was about using the quite same approach myself before reading. 

PS : I've read the French translation of the book. I'd recommend keeping all the class/method/etc things related to development as English words. Translate them is not relevant and confusing if the drawings are still in English

What do you mean ? I'm not sure to understand "do you have" ?

Well there are many possibilities like template, Factory and Bridge

Due to end of session the post is incomplete : 

Hi everyone,

Just finished this book along the Python examples. Was great.

However, I'm not sure what pattern is correct for my project:

• the goal of this project is to produce different pdf from the same data
• data for all document is centralized in a DB
• At first data are provided by a web form to fill in a db
• According to parameters given as inputs, the end product is a document which type relies on the inputs
• the types of docs may of course vary to a simple page doc, to multiple pages, fantasy colors doc, sober, etc

Here is a picture of the whole process.

So my question is what is the most appropriate design to implement the db to docs process while I found many of patterns could apply ?

Thanks

David