If anyone want to actually create one, the printable paper craft dragons are found below. They are from grand-illusions.com.
The video below shows a demonstration of how to create one of these optical illusions for anyone having a difficult time with the instructions.
Here are some other designs I came across. There are also designs for Halloween which are perfect given the nature of the illusions created.
The author of the robot dog design can be found (here).
The source of the cat design is located (here).
The skeleton can be downloaded with instructions from its official site (here). The Frankenstein head in a box is much more complex than any of the other paper crafts mentioned so far. With that said, here is the (source). All of the required pieces and instructions are at the site.