I was quite amazed to see this latest technology from Rabbit Proto. I certainly believed something like this was in the pipeline, but didn't expect to see integrated 3d printed circuitry anytime this year. Rabbit Proto, this week introduced a new open source extruder capable of fitting onto any Rep Rap dual extruder printer, and printing out a conductive ink. The ink can be printed during any printing process. The system makes it possible to print objects with integrated circuitry, all in one print without the need of having to switch print heads or any of that hassle.

http://3dprint.com/2674/rabbit-proto...ted-circuitry/

They are currently selling several packages which can be viewed in the link above. The technology is totally open source so you can pretty much build it yourself if you are capable. The files are located on Github. Here is an interesting video of what the Rabbit Proto is capably of printing: