Billybob884 of deviantART has developed a Papercraft style Master Chief model. The final product "comes out to be 13" (33 cm) tall, has roughly 2,100 faces (+ ~800 for the gun), and is made up of 42 pieces (+ 10 for the gun)." If you want to give it a go follow the link and print out the instructions, PDF pieces, and grab the model file. They say it is not a model recommended for beginner paper-folders. And they weren't lying. Mine turned out a lot less like Master Chief and a lot more like a crumpled green paper turd that the cats are batting around.
Master Chief Assembled [deviantART]