Abstract: A modular fluid handling device includes at least one block having opposing block faces shaped as tessellating regular polygons, and a series of block sides therebetween. Each block includes a central bore extending between the block faces, and channels extending into the block sides and intersecting with the central bore. The blocks may be rapidly horizontally and/or vertically affixed with their channels and/or bores in communication to form a fluid handling device having the desired configuration (e.g., with the channels/bores forming a desired process flow path, fluid circuit, or the like). Inserts complementarily fit within the bores of selected blocks can then bear components such as valves, filters, turbines or stirrers, heating or cooling elements, pumps, sensors, or other equipment, so that a block can be adapted to fulfill desired purposes by simply installing the desired inserts.