While Feynman first suggested it in 1959, the idea that we should eventually be able to economically arrange atoms in most of the ways permitted by physical law has only recently gained general acceptance.
Programmable self replicating molecular manufacturing systems should be able to manufacture products at low cost (perhaps a dollar per kilogram or less) while providing remarkable flexibility (making most structures consistent with physical law) and the ultimate in precision (getting almost every atom in the right place).
This is a powerful vision, but we are still many years away from achieving it. How should we proceed?