With the scientific foundations of touch established, this chapter begins the transition from understanding to building—from the natural mechanics of skin and perception to the engineered systems that seek to replicate them. It considers how the physical laws that govern deformation and sensation can be translated into the design principles of hardware, and how the quality of what is sensed ultimately shapes what can be known. Rather than treating sensors as instruments of measurement alone, the chapter frames them as the physical layer of an inference process: as devices that must not only detect mechanical events, but also encode them in ways that preserve perceptual meaning. By tracing the evolution of haptic hardware and examining the shift from measurement-centric to inference-centric design, the chapter positions hardware as the source of the informational substrate, data, upon which software and application subsystems will build.