Focused-ion-beam chemical vapor deposition (FIB-CVD) is an excellent technology to form three-dimensional nanostructures. Various three-dimensional nanostructures such as an inductance. a capacitor, a resistance, and a filter-circuit have been demonstrated by applying FIB-CVD with phenanthrene (C14H10) source gas using a computer-controlled pattern generator (CPG). The electrical resistivity measurement of the free-space-nanowiring was carried out by two terminal electrode method. The resistivity was 1 x 10(2) Omega cm in the case of using C14H10. To reduce the electrical resistivity, tungsten hexacarbonyl [W(CO)(6)] is added to C14H10 as a source gas. Increasing content Of W(CO)6, the electrical resistivity becomes lower from 1 x 10(2) to 2 x 10(-2) Omega cm at room temperature. By using free-space-nanowiring fabrication technology the world smallest nanomechanical switch composed of a coil and a nanowiring has been fabricated and confirmed the switching operation by applying a voltage. (C) 2004 American Vacuum Society.