The DIYLILCNC is a fully functional, open source 3-axis CNC that you can build with basic tools and parts that can be locally sourced. The idea is that you develop a 3D design in a CAD application, put feedstock into the CNC, and print your design to it, and it cuts and grinds away everything but what your design is supposed to be. Total cost of construction is about $700us. You can download the plans and DXF template files from the website for free (they have a CC-BY-SA license).
RepRap is an open-source (hardware, software, and documentation) desktop fabrication system which lets you construct arbitrary objects (or parts for assembling more complex systems). It's unique in that you can construct one yourself for about $400us, and it is fully capable of making duplicates of itself.
An open source DIY robotics/rapid prototyping kit much like an Erector set. Lots of standardized pre-milled bars, rods, connectors, and components. Build your own plotter, CNC machine, RepRap, scanner table, or what have you. Capable of three axes of linear motion. Comes with all the electronics you need, including an Arduino, stepper motors, and a motor driver board.
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