RepRap
"RepRap is humanity's first general-purpose self-replicating manufacturing machine.
RepRap takes the form of a free desktop 3D printer capable of printing plastic objects. Since many parts of RepRap are made from plastic and RepRap prints those parts, RepRap self-replicates by making a kit of itself - a kit that anyone can assemble given time and materials. It also means that - if you've got a RepRap - you can print lots of useful stuff, and you can print another RepRap for a friend...
RepRap is about making self-replicating machines, and making them freely available for the benefit of everyone. We are using 3D printing to do this, but if you have other technologies that can copy themselves and that can be made freely available to all, then this is the place for you too.
[...] RepRap was the first of the low-cost 3D printers, and the RepRap Project started the open-source 3D printer revolution. It has become the most widely-used 3D printer among the global members of the Maker Community.
[...] A family using one RepRap to print only 20 domestic products per year (about 0.02% of the products available) can expect to save between $300 and $2000:
'...the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average US household already.'
~ B.T. Wittbrodt"