But, as counter-intuitive as it sounds, pure water is actually an electrical insulator. It's only when you add electrolytes and minerals does it become the electronics-destroying liquid that we're most familiar with.
Knowing that, with careful planning, you should be able to construct 3D circuitry with nothing more than carefully planned paths of frozen electrolyte-rich water among a larger bath of pure water or mineral oil.
In a weird way, it's almost like 3D printing, only with frozen water instead of plastic! That could be an interesting next step for this project (3D printing circuitry). But, before then, you'd have an important problem to solve: Circuits are warm, and ice melts when it gets warm. All else fails, you could just leave the circuit in your freezer.
Heh. If you did that, imagine the overclocking potential! Your entire circuit would serve as a huge, frozen heatsink. That's not even liquid cooling, that's ice cooling! (Though, we don't recommend trying this with your computer. Modern CPUs aren't designed to operate at freezing temperatures).
It's absolutely a crazy idea - but one that we're dying to try out. If you try making your own 3D circuit, let us know in the comments!