"Bottom-UP - An approach to building things by combining smaller components, as opposed to carving them out of larger ones (top down), as is done in current photolithographic approaches to making silicon chips. A car engine is assembled, this being a bottom-up approach, while some of the components might be machined, i.e. sculpted out of chunks of material, this being top-down. The sculpture analogy illustrates how bottom-up approaches will generally involve less production of waste material. Currently, techniques are evolving using both approaches and many applications are likely to involve a combination of approaches, but the bottom-up approach is far sexier, and is usually exemplified by self-assembly or molecular assemblers, i.e. nanomachines that can be programmed to build structures an atom or molecule at a time (check out www.foresight.org for more on this futuristic idea)." CMP-Cientifica