What about Copyright?
PrintFu never looks at the content of the printed content. PrintFu is only a remote printer. The user is responsible for their own rights to the printed content.
Hmm. I think such a service should be legal, but I don't think "we never look at the content" is the standard. MP3.com got into trouble trying to use the delegated and indirect fair-use rights of its customers -- who had even "proven" (after a fashion) their possession of a legal physical copy. My magic 8-ball says for PrintFu: "Danger ahead. Watch your back."