The Shapeoko is an open source CNC that you can either buy as a kit or build yourself for about $300us. Work up your design on a laptop using open source CAD software, clamp feedstock on the bed, and it'll produce what you designed. Because it's open source it's not limited to wood - it could be adapted to just about any material that you can cut or grind could be. Chances are, someone's already done it and posted the docs.
Everything is also kept in a respository on Github: https://github.com/shapeoko/shapeoko
4985 links, including 378 private