What you could use as an option is the PDF viewer from mendix. after creating the document you can show it to a user, and there the user has buttons to either print or download the document
Not sure if this is an option in your case, but you could also decide not to create a PDF, but to create a regular page instead with a layout that is acceptable to print.
I hope this helps.
The user should not be able to see any type of document. He just needs to fill in a form and and when finished, a document is generated (NOT SHOWN to the user) and this generated document (=FileDocument) should be sent to a printer directly.