I was fascinated about six years ago to see a black and white picture of a machine moving an atom from one place in a lattice (I think it was a metal) to another place. The possibility of creating materials one atom at a time suggests the making of perfect crystals (one person suggested a house built entirely out of diamond) or sheets of metal. The idea that materials could be thinner ( a few atoms thick) and contain no flaws making them much stronger would not only revolutionise how we make everything but also give us the arcane materials we know we will need for space travel.
The future never arrives smoothly. Most of the materials we use are not single elements, but compounds and creating those one atom at a time is not at all straight forward. That might be because in the real world compounds are thrown together and happen to make themselves into something different through chance bonding. In a nano technology machine all chance is taken away.
It may be that life is more about its flaws than about its design, which would accord with what we know of thought, and the constructs humans make. We have never created anything using adequate reason but a compound of necessity, chance, climate, luck and feelings.
I doubt that compound would get us across the universe but we may be stuck with it.