Attitude Determination is critical for many CubeSat class satellites. However, the mass, volume, and power constraints of the CubeSat form factor limit the options available to designers. In this work, we are developing a Stellar Gyroscope to generate spacecraft relative attitude estimates in three degrees of freedom without the drift associated with most solid state based gyroscope approaches. A Stellar Gyroscope is a star based attitude propagator that uses relative motion of stars in an imager's field of view. Algorithms to perform the star detection, correspondence, and attitude propagation are presented. The Random Sample Consensus (RANSAC) approach is applied to the correspondence problem to mitigate false-positive and false-negative star detections. This paper overviews the approach, describes the details of the solutions for the challenging aspects of the approach, evaluates experimental results, and offers component selection for a preliminary designs for a CubeSat system.