One of the most exciting technologies in development right now? The 3D printer.
It seems that most people who aren't geeks don't know anything about this.
A 3D printer is a fairly simple concept that's not dissimilar from the inkjet printers most of us have these days (If you have a photo printer, it's an inkjet, and most small desktop printers are inkjets.) Instead of extruding ink from the jet, the 3D printer extrudes plastic, metal, or whatever you need. 3D printers have been used for all kinds of purposes. Plastic printers can, for example, create a missing part for an old Airfix kit. Some restaurants have 3D printers that extrude dough, allowing the creation of intricate confectionaries that would be hard or possible to do by hand.
The cheaper kinds of 3D printers are now within the reach of individuals at prices comparable to a high-end laser printer.
But this is not what is truly exciting about 3D printers.
3D printers have been used to create muscle, cartilage and bone. There are 3D printers in existence right now that can be fed a small amount of cartilage taken from a person's joint and print up an ear - just add skin.
Medical researchers are hopeful that within a matter of not decades but years, they will be able to literally print replacement organs. They hope that bone printing will be approved in a year or two, potentially allowing the repair of complex fractures that until now have required amputation. In the longer term future, printing up somebody a new arm or leg, or at least the framework to allow that person to grow one, is now feasible. Not technically there yet, but feasible.
In the future, nobody will need a prosthetic arm or leg, but only an outer framework to temporarily support the limb and perform its purposes while it regenerates (such already exist). In the future, we will be able to grow somebody a new heart, lung or liver, from their own tissue (so no rejection problems), but with whatever defect or deformity was causing them to need one corrected.
And there may be other implications. Who remembers the Star Trek episode 'What Are Little Girls Made Of?' In that episode, the sinister Korby creates android copies using a blank and a device that might well be a highly sophisticated 3D printer.
More obviously (thank you Nobilis for pointing this one out) the recreation of Leeloo in the Fifth Element is definitely 3D printing.
Now there is a can of worms...are we ready for factory-made clones?