Read Managing Magic by the Center for Responsible Nanotechnology. Here's how it begins:
"It seems like magic. A small appliance, about the size of a washing machine, that is able to manufacture almost anything. It is called a nanofactory. Fed with simple chemical stocks, this amazing machine breaks down molecules, and then reassembles them into any product you ask for. Packed with nanotechnology and robotics, weighing 200 pounds and standing half as tall as a person, it can produce two tons per day of products. Control is simple: a touch screen selects the type and number of products to produce. It costs very little to operate, just the price of materials fed into it. In one hour, $20 worth of chemicals can be converted into 100 pairs of shoes, or 50 shovels, or 200 cell phones, or even a duplicate nanofactory!"