The other routes to Nanotechnology are more likely to lead in the short term to custom products and not to general purpose manufacture. * The bottom up route, using Biotechnology, is constrained by being adaptations of existing naturally occurring protein and enzymes and our custom derivatives. * The third route via Lithography, leveraging the photographic-reduction process used in modern chip manufacture to produce micro machines (SEMS), is also less likely to lead to a general purpose Nanofactory. The reason is that that technology is planar, and silicon based. Moving to 3D and other non silicon-like materials is very hard.