Molecular manufacturing is the hypothetical future use of reprogrammable nanoscale "assemblers" to build products atom by atom. A molecular assembler would be a nanoscale robotic manipulator capable of placing single atoms, for example carbon, onto a surface with atomic precision. An everyday person would experience this technology in the form of a "nanofactory," a self-contained desktop molecular manufacturing unit that uses a purified feedstock material, such as propane gas.
For a molecular assembler to be useful to humans, it would have to be able to make copies of itself. Otherwise, it would take too long for a single assembler to build anything of significant size or value. If a large array of assemblers could be made to cooperate, they could construct macroscale products with atomic precision, using a fully automated process with high throughput. This is significant enough that, if the technical obstacles are overcome, the technology would launch another Industrial Revolution, probably more transformative than the first two put together.
Molecular assemblers and molecular manufacturing are nothing new. We have trillions of them in our bodies: organelles called ribosomes. Working in large numbers, ribosomes synthesize every protein in every organism in nature, from extremophile microbes to the blue whale. Their basic design is all the same, because every living thing evolved from a common ancestor that already had the basic protein synthesis machinery in place. Of course, ribosomes are also self-replicating.
If an inorganic molecular assembler were created capable of making copies of itself, it could create a new form of "life," albeit a type controlled directly by programming. This idea has been called molecular manufacturing, and some of the technical details for it have actually been worked out. Theorists have designed physically-viable nanoscale gears, motors, batteries, wires, moving rods, sorters, shafts, and more. Some of these nanoscale devices have already been fabricated, others are being actively worked on.
Molecular manufacturing has the potential to turn society upside-down, but barely anyone has heard of it. Often, the ideas of molecular manufacturing are combined or conflated with other possible applications of the wider field of nanotechology in general, which makes it difficult to come up with regulation policies for the latter. One study found that public opinions on nanotechnology could easily be manipulated by changing just a few sentences in the way the topic is introduced. These gaps in knowledge are worrisome to some futurists and policymakers, who would like to see more discussion on the futuristic possibilities of molecular manufacturing, and the way it might be regulated.