We report the design of an analog technology, what we refer to as a SunRule, that uses sunlight to model multiplication. Physical models that explore multiplication are fixtures in elementary mathematics classrooms. Our interest in physical models of multiplication was driven by an overarching design problem: How could a physical tool realize a continuous model of multiplication? That is, how could we represent continuous, variable quantities with physical things? We identify specific challenges the SunRule was designed to solve. We explain the mathematical underpinnings of the device and report a teaching experiment during which preservice teachers explored the device in small, socially-distanced groups. We consider how explorations with the SunRule create opportunities for mathematically rich instructional activities that are also essentially connected to being outside. [For the complete proceedings, see ED630060.]