I highly recommend Engines 2.0 rather than the original. Drexler's conception of nanobots before he had done the heavy lifting of working out the designs that

I highly recommend Engines 2.0 rather than the original. Drexler's conception of nanobots before he had done the heavy lifting of working out the designs that showed up in Nanosystems probably aren't very practical compared to more factory assembly line structures. Thermal motion is just so much easier to deal with in an enclosed tube than at the end of a wobbly arm.