Now that we're operating in that variety of invention, why not come up with a neat economical method for converting lead to gold.

3D lithography has been around for years, essentially the same idea except artifacts are replicated from CAD files into clear plastic form. Desktop 3d lithography could be just around the corner, it might be possible to fax a plastic copy of a coffee cup or an ashtray reasonably soon. More complicated items, metallic items, and ham sandwiches will take awhile longer.

It is one thing to fabricate a three dimensional form from a uniform plastic whose solidification can be controlled by digital mnipulation. To reproduce an object from many diverse materials requires processes far beyond current technology. A totally different fettle of kitsch.

Admittedly, not something one can whip up in a basement workshop over a long weekend. A number of technologies have to be developed further- for example, desktop 3D scanners would need to become much more sophisticated, and at the same time a LOT cheaper (the one I have my eye on is "only" $20,000). Current 3D lithography uses a vat of light-sensitive resin, using more than one material would require anoither trick- vacuum vapor deposition?

If you are not planning on transmuting a basic anonymous matter bank into the various materials required for the final product, you must keep on hand a monstrous collection of various materials to be processed. Beyond this fundamental problem, just duplicating an element or an alloy is not sufficient. The precise crystaline structure is required for specific physical characteristics such as surface hardness, flexibility, optical characteristics, etc. Our current technology is nowhere near that capability. It requires total and precise control of atomic structures.

I think if we start out with one-piece, monochrome plastic items, then progress to multipart, multicolor plastic items, the overall usefulness of the device will eventually demand more technological sophistication and more capability. It wasn't so long ago that scanner/printer/fax/copiers were beyond our technological capabilities. Now they're available under $100.

It is difficult for me to determine whether your unwarranted optimism is due to naivete´or you have somehow hooked into a time machine. The latter seems unlikely.

I suppose the Apollo Program, even spaceflight in general, once looked impossible to some, as did Polaroid photography, digital cameras, music CDs, cell phones, home computers, heavier-than-air flight, lighter-than air flight, internal combustion engines, communication satellites, suffrage for women, ending slavery, or living somewhere other than caves. Many people, at one time or another, ridiculed all of these ideas as "impossible."

Actually, stereolithography isn't the only form of "3D printing". There's a whole range of what are known as 'rapid prototyping' techniques. If anyone's interested there's a pretty comprehensive website - http://www.cc.utah.edu/~asn8200/rapid.htmlalso, Hewlett-Packard are interested in the technology, see - http://computer.howstuffworks.com/news-item115.htm

"Desktop" 3D printer, price starts at "only" $24,900.

http://www.dimensionprinting.com/3Dprinting.html

Operates from files in several CAD formats.

The second your learn to send matter over a wire is the second you turn matter into information, and hence make it copyable. This ability would be more devastating than anything.