20th Century hype about nanotechnology went in two directions. We would either be making everything with Star Trek style fabricators, or the world would be swamped in grey goo. Neither has happened, needless to say. Nanotechnological fabrication has simply proved too hard a problem to crack. Whilst in theory possible, the fundamental problem is that each individual nanomachine does not know its exact position in the matrix; it does not know exactly where to lay the next atom or molecule. You might try to manufacture a car and end up with a vaguely car shaped lump of assorted materials. In biological systems, individual cells “know” where they are and where to grow (hence we humans conform to a pretty uniform shape, both externally and internally). Attempts have been made to mimic the type of biochemical signalling involved, and have met with some success, especially in micro-manufacturing. However, the technology is still years away, and it is still simply cheaper to build things the old-fashioned way. However, where nanotechnology has excelled is in areas where position doesn’t matter. Advanced chemistry, if you will. For example, nanomachines based on viral structures, which can clean the blood of specific target chemicals. Cleaning products that can simply melt away dirt and stains. And nanomachines specifically designed for work inside industrial processes – recycling vats, previously impossible chemical reactions, substrates for quantum-level semi-conductors. The list is almost endless. But why did apocalyptic visions of grey goo engulfing the planet never come true? Simple: economics. Manufacturers don’t build self-replicating machines. They want you to keep buying from the source.