The ultimate 3D printer would be something like the replicators in Star Trek that were capable of creating anything. That, of course, may never be possible, and most 3D printers these days just work with thermoplastics. But, researchers from the University of Hamburg have created a remarkable 3D printer that is a big step towards those replicators.
Their design started off as a standard FFF (fused filament fabrication) 3D printer — just like the kind you could order online for a couple thousand dollars right now. They then upgraded it with an OctoPNP camera-based PNP (pick ‘n place) system for placing components. Finally they added a second extruder that is the syringe pump style, which is capable of printing conductive paste.
When all of those pieces come together with their custom Slic3r extension, the printer can make entire electronic devices. The plastic case of the device is printed as usual, and then lays conductive traces into channels. Components can then be placed manually or automatically with the PNP capabilities. Then, more layers of plastic are extruded to lock everything into place. As you can see in the video, the system works well and they were able to print a small widget that turns on an LED when a button is pressed.