Not worth the paper it is written on of no value or validity despite having been written down.
paper over the cracks use a temporary expedient, or to create a mere semblance of order. The phrase is a translation of a German expression used by Otto von Bismarck in a letter of 1865, and early uses refer to this.
paper tiger a person or thing that appears threatening but is ineffectual. The expression became well-known in the West from its use by Mao Zhe Dong in an interview in 1946.