Papercraft is something new to me. I have always known of origami, but this is something entirely different! The concept is simple. Print out a sheet of paper and cut out the design. Then start folding until your character is built! Cubecraft.com is a good place to start. The designs are simple and easy to assemble. If you want to build something amazing though, you will need to start searching google and find someone who posted their desing online, like this one!
Here are some sites to get you started with Papercraft: