With privacy locks, you just need to get the paper clip in deep enough to touch the pressure plate inside, and the door can be opened by twisting the knob.

Most projects we feature are of the metal/wire/wood variety, but there is an entire community devoting to making very interesting and intricate things out of paper. Imgur user [Criand] has been har… ...

His paper version borrows the same principles of more robust locks, and the instructions are available for download.