I designed this model earlier this year. I began by designing a rather simple dog head. Then I used border grafts to add the butterfly. The base is quite versatile and the butterfly could be modified into many things. It is quite satisfying to fold and not very tricky, provided you have the experience required for an inermediate.
To fold this model you will need one square sheet of paper with two colors (keep in mind that the dog head and butterfly are the same color). Paper size depends on finger dexterity and paper thickness. Basically I would advise using anything you would be comfortable folding a 16x16 grid with (though we won't actually be doing that) and having it a few layers thick in the final model. If you are still wondering what to use, a 10 inch (25 cm) kami works just fine.