TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Method: The frames are formed from a frame material by molding, casting, stamping, printing, ablating, etching, machining, water jetting, and/or forging. The step of forming the intermediate assembly comprises making a structural form that prevents reactant from one reactant plenum from moving into the other reactant plenum. The barrier is formed from barrier material and joined to at least a portion of at least one process layer. The step of forming the intermediate assembly further comprises creating process layers with a defined shape from the group: a rectangle, a square, a triangle, an annular ring, an arc, or an arbitrary pattern. At least a portion of one of the low aspect ratio cavities is filled with a material to facilitate the transport of reactant material or transport of reactant attributes. The material used to fill the low aspect ratio cavity forms a micro-structure. The step of joining intermediate assemblies comprises joining 2-100000 intermediate assemblies to form the compact chemical reactor. The perimeter barrier is formed on the process layer by welding, adhering, clamping, screwing, or otherwise engaging the perimeter barrier to the process layer. The step of forming the intermediate assembly comprises making at least one of the process layers an undulating process layer. Preferred Component: The flame material comprises an electrolyte, an ion exchange membrane a filtration membrane, a separation membrane, a micro-structured diffusion mixer, a heater, a catalyst, electrical conductors, thermal conductors, a filled metal composite, a filled micro-structure of polymer, a filled epoxy composite, and/or a graphite composite. The structural form can be a micro-structure or a three dimensional structure (40) with a tortuous path. The material used to fill one of the low aspect ratio cavities comprises a catalyst, a porous material, an electrical conductor, and/or hydrophobic polymeric binder. Each process layer comprises an electrolyte, an ion exchange membrane, a proton exchange membrane, a filtration membrane, a separation membrane, a micro-structure diffusion mixer, a heater, a catalyst, an electrical conductor, a thermal conductor, a micro-structure of a polymer, a filled micro-structure of a polymer, a filled epoxy composite, a filled graphite composite, a filled metal composite, and/or plastic.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The perimeter barrier comprises a metal, a silicone, a rubber, a polyamide, a synthetic rubber, an epoxy, polytetrafluorethylene, polyvinyldifluoride, an ion exchange material, a proton exchange material, and/or their composite, a laminate, and/or an alloys.