This research provides a foundation for manufacturing multi-layered metal laminae with microfluidic, micro-feature devices for use in a high temperature and high pressure environments. A reliable method of joining metal laminae could help make the manufacturing of instant reaction heat exchangers and chemical mixing in a cost effective, reliable, and simplified method. These devices enable faster reaction times, modular scaling of production capacity, on-demand chemical processing, and higher purity products. This could lead to faster rates of adoption of microreactors in industries such as pharmaceuticals, energy, food, and bio-medical. Eutectic brazing avoids damage to internal surface geometries and deformation due to lower temperatures required for bonding compared with higher-temperature joining processes. A new process was developed to combine multiple layers of 6061 aluminum alloy with copper foil interlayers to produce micro-channel micro heat exchangers and reactor devices that could be used for new applications. This process repeatedly produced leak-tight devices. The prototype devices contained overlapping coolant and reactant channel systems arranged perpendicularly within each lamina. Related work suggests that diffused joints are mechanically robust in contrast to the parent materials.