This paper presents a method for geometric machinability analysis. The implementation of the strategy determines the machinability of a part being processed using a plurality of 3-axis machining operations about a single axis of rotation for setup orientations. Slice file geometry from a stereolithography model is used to map machinable ranges to each of the line segments comprising the polygonal chains of each slice. The slices are taken orthogonal to the axis of rotation, hence, both two- and three-dimensional (2D and 3D) machinability analysis is calculated for perpendicular and oblique tool orientations, respectively. This machinability approach expands upon earlier work on 2D visibility analysis for the rapid manufacturing and prototyping of components using CNC machining.