This device was printed out using a 3D printer. No assembly required!
Brain Gear - Download and Print
This puzzle contains almost 1000 moving parts.
The Petaminx - Download and Print
Build instructions for the simplest RepRap, includes a parts list and videos of the setup process http://reprap.org/wiki/Prusa_Build_Manual
It works by heating and extruding a thin plastic wire that is purchased as large spools - PLA Clear 1kg spool 3mm. The material that is printed can actually be made from a plant material that would set the way for using broken items as compost. The two common materials used for printing are ABS and PLA. Both are easily purchased but the one I'd recommend is the PLA as it is the material that is made from plant starches and is biodegradable. While the PLA can be home grown the purchased spools are going be stronger.
The fact that PLA can be biodegraded, and re used to grow more PLA makes it much more attractive for me. One of the main problems with traditional plastics is the fact that they do not biodegrade easily.
The third world, and manufacturing centers like Taiwan and China are covered in plastic garbage that does not decompose and does not go away, and can not be recycled into quality goods. If switching to PLA will reduce that even a little bit, I think it would be a huge advantage.
ABS is the stuff legos are made out of and PLA is made from corn.
TED Talks - We Can Recycle Plastic ( if you just have to print with ABS this should make you feel better)
Aside from just printing plastic parts the RepRap can print out metals that allow it to print circuit boards, but not processor chips, there are other types of adapters that are in the works though.
This is the man that started the RepRap, Adrian Bowyer
Watch the RepRap print a simple part and listen to the info about the RepRap.
Having an awesome 3d printer wouldn't be quite as awesome if there wasn't a library of free files to download and print at anytime. There is the RepRap Object Library which is a good place to start for beginners. It has objects available to download and print, but also contains learning resources and links to get going creating your own objects to print. Another place to get free files to download and print with the RepRap is Thingiverse, which is a great site.
Here are some examples from Thingiverse
Vogal The Dragon
Where the RepRap project scores over large scale manufacturing is the ability to promote quick innovation and "Distributed Thinking". An example of that is on the website Thingiverse any item uploaded, can be altered by another user and re-uploaded, and Thingiverse shows this. The website let's users say that their object was derived from so and so, and will also display that it has 13 variations of it's own and so on.