But its not quite a modular. The paper is assembled via a method called 'snapology'.
Basically, i take a large square, say 30 square cm for instance, and I will cut it into 1:10 strips. You don't have to use those proportions exactly, but i find that those tend to work the best. anywhere from there to 1:12 will give you good results.
Afterwards the paper is then folded over on itself over and over again as to form a grid on the strips of paper. You then cut those into appropriate sizes to form the shapes, and then start weaving the paper together.
It is really difficult for me to explain im afraid, but here is a [link] to the website that details maginifcently how to construct a basic icosahedron. Once you have that model down, you can use this method to assemble any platonic or Archimedean solid!