do you guys know any "document assembler" implementation?

Please explain what you mean.

I want to create documents that are made of blocks. They don't have to follow any specific logic (like what happens to chatbots), but they do need to be provide me the chance to mix between paragraphs and etc. For example: I have block 1, block 2 and block3. Each of them represent a paragraph, and together they represent a document. Basically I would like to be able to give the user the opportunity to work and mix these "blocks of words".