We propose a scheme to revolutionise the synthesis of nanodevices, nanomachines, and, ultimately, functional materials via the positional assembly of molecules and nanoscale building blocks. Computer-directed actuators will be used to drive (with sub-nanometre to sub-Angstrom precision) the elements of a nanosystem along pre-defined and entirely deterministic trajectories, thereby achieving structures not accessible by mimicing natural assembly strategies alone. Linkages and bonding between the building blocks will also be initiated, modulated, and – in some cases – terminated by direct computer control. Our proposal rests on the parallel development of novel surface-bound, reconfigurable nanoscale building blocks (molecules, functionalised clusters, nanoparticles) and a prototype computer-controlled matter manipulator best described as a nanoscale conveyor belt. We focus on the generation of two major and immensely challenging functionalities for positionally-assembled nanomachines: switchable energy transduction and conformationally-driven motion. Our archetypal system comprises the following units: an energy harvester, a switchable/gateable link, and an optical or mechanical output. By arranging, configuring, and triggering these fundamental units our long-term goal is no less than the fabrication of an autonomous, abiotic [non-living] nanomachine.