Everybody knows how a printer works, put in a blank paper and comes out a paper with picture or drawing on it, a couple of years this idea was developed further, what happens if instead of depositing a single layer of material, the machine deposits many layers of material? You have a 3D printer, it isn’t sci-fi anymore, many rapid prototyping companies use this technology, the Olympic stadium in Beijing was modeled using a 3D printer, did you know that a 3D printers costs about 4-5000$, and it is estimated the price will drop to 1000$ in four years.
How does the 3D printer work? Well it is similar to a 3D CNC machine, it can move one of its parts in X,Y,Z plan, but instead of attaching a mill, they attach a plastic extruder, so instead of milling away the excess material, they deposit layer by layer the plastic. By doing so the machine can make more complex parts, there are many technologies, some machines deposit a fine layer of melted polyester, or dust and so on.
There are a bunch of manufacturers which sell these printers, but a group of open minded people said, why not make a cheap affordable machine, which can be put together in a garage, the idea goes even further, they want to make a machine which is capable of replicating itself, no wonder the first version was named Darwin. You can buy as a kit, or you can download the design and try to make it yourself from scratch, you can find allot of tutorials, videos, free soft but even so, it is a complex machine.
Probably will pas a couple of years until a true self replicating machine will be built, the material supported is plastic, the metal parts, like screws and motors need to be purchased separately.
Self replicating hardware: [Link]