] In their printing process, Epson uses two types of ink to
] produce circuit boards. The first is a conductive ink and
] the second is an insulator ink that is used to separate
] each layer from the next. This allows a printer to paint
] these inks in patterns on top of each other in an
] extraordinarily compact manner. In fact, the 20-layer
] board shown today looks only to be a a millimeter thick,
] if that.

I met a Brit at Foo camp who works for a Canon, researching this very thing. He discussed being able to "print" a fully working Cell phone that you buy online in the nezxt 15-20 years. Now, whether the end user will pay for basically a small factory when they are only "printing" the occasional purchase is up for debate, but its cool to see advances in this area.

Epson uses inkjet technology to print circuit boards