NOVELTY - The production method involves forming a layer of density-changing material on a substructure, and forming a support layer on at least a portion of the layer of density-changing material. The density-changing material has a first density during formation of the layer, and a second density subsequent to the formation of the support layer. The second density is greater than the first density, such that the layer of density-changing material shrinks in at least one dimension to provide a gap (8) between the layer of density changing material and at least one of the support layer and substructure.    USE - Production method for making electromechanical device used in electromechanical system (all claimed). Can be used in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS) which are used in e.g. radio frequency (RF) applications, mobile technologies, photonics, energy, solar cells, telecommunications, transistors and diodes.    ADVANTAGE - Allows the fabrication of structures having nanogaps which are significantly smaller than 1 micrometer and can be as small as a few nanometers in size, or even less than 1 nanometer. Simplifies fabrication of MEMS devices by avoiding encapsulation or other protection procedures such as sealing. Allows for the fabrication of vacuum gaps that do not need special sealing or protection against ambient atmosphere. Allows for fabrication of gaps inside the material, such that the gap automatically provides a vacuum relative to the surrounding environment.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a combined electronic and electromechanical device;    (2) an apparatus comprising an electromechanical system;    (3) a waveguide producing method; and    (4) a waveguide device.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic illustration of the production of an electromechanical device.    Substrate (1)    Isolation layer (2)    Bottom layer (3)    Top layer (4)    Structure (5)    New material layers (6,7)    Gap (8)