Rapid 3D optical scanning of points or patterned light is widely employed across applications in microscopy, material processing, adaptive optics and surveying. Despite this broadness in applicability, embodiments of 3D scanning tools may vary considerably as a result of the specific performance needs of each application. We present here a micromirror arraybased modular framework for the systemic design of such high-speed scanning tools. Our framework combines a semicustom commercial fabrication process with a comprehensive simulation pipeline in order to optimally reconfigure pixel wiring schemes across specific applications for the efficient allocation of available degrees of freedom. As a demonstration of this framework and to address existing bottlenecks in axial focusing, we produced a 32-ring concentric micromirror array capable of performing random-access focusing for wavelengths of up to 1040 nm at a response rate of 8.75 kHz. By partitioning the rings into electrostatically driven piston-mode pixels, we are able to operate the array through simple openloop 30 V drive, minimizing insertion complexity, and to ensure stable operation by preventing torsional failure and curling from stress. Furthermore, by taking advantage of phase-wrapping and the 32 degrees of freedom afforded by the number of independently addressable rings, we achieve good axial resolvability across the tool's operating range with an axial fullwidth- half-maximum to range ratio of 3.5% as well as the ability to address focus depth-dependent aberrations resulting from the optical system or sample under study.