The video below shows you the exact process of building a 3D model using advanced inkjet-based 3D printing. Starting with the initial design on the screen of your CAD software - the 3D printer then proceeds to lay down individual layers of liquid photopolymer resins - that are jetted at a rate of millions of droplets per second from inkjet heads very similar to those in standard paper-feed printers. The difference is that this liquid is then hardened or 'cured' by a UV light that follows the print head on each run - thereby 'building' each layer before the next layer is applied. After this process is repeated thousands of times - an accurate 3D model prototype can be removed from the printer - produced in much faster time and at a fraction of the cost of a traditionally manufactured prototype part.
Got that? Now let's take it a step further. Imagine that instead of being limited to just one type of resin, the 3D printer is programmed to jet 2 materials at a time (a capability that's unique to inkjet among the various types of 3D printing technologies).
So now you can create composite materials of different shades and flexibility levels - and also create far more life-like models - consisting of different materials designated to different features of your model. Notice the amazing model of the human torso here on the left - you have a see-through shape printed in one material, that allows medical practitioners to view and expertly evaluate the bone structure inside that's printed in another material.
And just to mess with your mind even further - consider that with Objet's inkjet-based 3D printing there's no seams between these two materials - they are grown together into a single strucutre from a single print job.
You know what? I'll leave it to these guys to show you more, since they do such a nice job.