SummaryWhen I learned that printing plastic and metal together is possible today and affordable soon, I realized the potential of the 3D circuit. Made in any shape, the metal and plastic inductors, resistors, and capacitors should be sized properly for RF circuits and of course any chip is fair game plus LEDs and maybe even polymer semiconductors someday soon. This version has the metal shapes for resistor, inductor, and capacitor. Soon I will make the other parts including wires, nodes, chips, etc. Then we can make 3D circuits. Imagine a remote control airplane with it's electronics integrated into the fuselage or a processor cube or stepper motor for some REPRAP of the near future. All those cool sci-fi images of circuitry etched into tools or weapons or instruments or ships themselves is now available to us. Like wow man... InstructionsFor a test circuit I decided to make an inductively powered LED. To accomplish this we need an RLC resonant tank circuit and an LED. I chose to create the RLC circuit as one combined circuit element in distributed parallel form. That is, it's a pair of inductor coils interwound so that a capacitance forms between the plates and an inductance forms along the length of the plates. There will also be inherent resistance due to the conductivity of the metal, hence RLC circuit. by attaching an LED to either end we can light the LED with an external magnetic field at or near the resonant frequency. See the example circuit, RLC LED resonator, for the geometry.