I guess this is less messy than copper prototyping (acid etching/gantry ablation/vectorboarding), but silver is more expensive, ~100x.<p>Also, -1 for "help start the home PCB printing revolution." Hobbyists have been making home PCBs for longer than I've been alive. It's not a revolution. Not that many people really want to do this. They could right now with copper, but the range of useful things you can build at home is limited, because having a circuit board is only 1/10th of the problem. Further, prototype services like <a href="http://oshpark.com" rel="nofollow">http://oshpark.com</a> offer high-quality services, including double-sided boards.
This is pretty awesome. And it is the first time I've heard of someone doing this with precipitate chemistry which seems really clever.<p>It also brings a lot of questions to the table which, when answered, will push electronics prototyping to a new place.<p>First is signal integrity issues. Getting some electrons from point A to point B is cool, getting them there along a path that consistently has the same impedence is a bit harder, do able though with sufficient control.<p>It's fortunate that many of the inkjet patents have expired, that kept this approach pinned up for years. I look forward to these guys getting funded and moving the prototype PCB market from a pint of etchant and a copper plated board, into something more advanced.
For this to be truly useful, there needs to be a way for traces to cross (usually accomplished with multiple layers plus vias). It seems it would be possible to add a second, insulating ink to print between traces at crossing points.
Wait - there's no 3D to this, is there? It would be more accurate to call this "Printing Circuits" than "3D Printing Circuits".