At the Bordeaux Geek Festival, we saw artists making fancy papercrafted models like this:
They used Pepakura Designer which automatically transform 3D model into a 2D printable format. Once the papercrafted model is made, they apply numerous treatment to make a solid and paintable structure. See: http://makezine.com/2012/11/09/prop-building-with-pepakura-and-papercraft/
A nice idea to make cheap parts, but it requires a lot of time and patience.