What exactly is rapid prototyping ?
Sometimes we get some great ideas; some ideas are forgotten due to it took too long to build other ideas.
But if we could just build our circuits as quickly as they came to mind, imagine how great that would be.
I recently learned about Circuit Scribe. This is some advanced technology that puts your best PCB layout application and laser PCB cutter to shame.
Circuit Scribe is a pen containing conductive ink. It's made by a company called Electroninks.
How long would it take to make a circuit using one 1.27mm pitch SMD microcontroller, which could blink a LED powered by a CR2032 battery ?
I believe that it would take less than 10 seconds. You wouldn't even have to worry about a resistor for the LED.
All you need is the microcontroller, a piece of paper, a LED, a 100nF capacitor, a battery and the conductive silver ink pen.
You don't have to wait for a PCB to be manufactured and you don't have to solder. Just draw the circuit on a piece of paper to the pins of the components - that will make the connection for you.
You can read their story here Circuit Scribe: Draw Circuits Instantly by Electroninks Incorporated — Kickstarter.
...I've heard some people are experimenting with creating printers that use conductive silver ink, but I do not know if they've made it to the market yet.
Combine with the Robox 3D printer, and you can have your final prototype quickly.
A group I meet with outside work is investigating PCB milling. It can also give good results in a shot time.
The various silver circuit solutions are mainly a novelty, but do have limited prototyping ability particularly with flexible circuits.
The big problem with either milling or conductive inks is that as soon as you move to any complexity and closely spaced pins on packages, you need tining and solder masks to make reliable circuits.
Four-layer PTH, tinned and masked boards are just a few days away, so no competition when you want a reliable compact prototype.