As a NSW resident, the 3D printing aspect is just one part. There has been some reporting of backyard manufacture of firearms, usually machine pistols. This legislation, doesn't just prohibit 3D printing blueprints, but also specifically prohibits blueprints for electronic milling machines as well (CNC mills).
This isn't going to change anything much at all. They didn't ban manufacture of firearms through these methods, the people who can legally manufacture firearms, are exempt from these restrictions. What is dangerous about it is that it's basically banning knowledge, to some extent. Will they ban drug recipes? What about chemistry books if they have instructions that can aid drug manufacture? The possibilties are endless, and that's where the US first amendment is such a powerful right, which few other nations have granted to their respective serfs.