custom-made prosthetic limbs. and believe it or not, scientists are even developing the technology to print human organs, and the machines that come to mind are kind of 3-d printers that layer through kind of a squirting process layer by layer build up something that looks like a physical object, but there are actually many, many different -- >> i've used every 3-d printer from the beginning. but that's among the least useful machines. it's like the 1950s telling the chef the future of your kitchen is a microwave oven. microwave ovens are good, we have them, but it doesn't replace the rest of the kitchen. >> if a 3-d printer is like a microwave, then what are some of the other kitchen appliances? at mit's lab there are high-powered lasers that can cut shapes very precisely allowing two-dwengs dimensional shapes to fit together to make three-dimensional structures. there are machines that cut wax for making molds and casting parts. there are water jet cutters where high pressure water pushds