NASA's Jet Propulsion Laboratory at the California Institute of Technology has released a complete detailed guide on how to build your own scaled-down Mars rover. The Open Source Rover is intended to be a challenge for anyone looking to get involved in the mechanical, electronics, software or robotics fields. The whole robot will cost you about $2500 to make and has a Raspberry Pi at its heart as the main controller. All of the parts and software needed are detailed on their GitHub page as well as some hints as to what to expect over the course of the build.