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 1×102 Ω 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 1×102 to 2×10-2 Ω 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.