Physical skill acquisition, from sports techniques to surgical procedures, requires instruction and feedback. In the absence of a human expert, Physical Task Guidance (PTG) systems can offer a promising alternative. These systems integrate Artificial Intelligence (AI) and Mixed Reality (MR) to provide realtime feedback and guidance as users practice and learn skills using physical tools and objects. However, designing PTG systems presents challenges beyond engineering complexities. The intricate interplay between users, AI, MR interfaces, and the physical environment creates unique interaction design hurdles. To address these challenges, we present an interaction design toolkit derived from our analysis of PTG prototypes developed by eight student teams during a 10-week-long graduate course. The toolkit comprises Design Considerations, Design Patterns, and an Interaction Canvas. Our evaluation suggests that the toolkit can serve as a valuable resource for practitioners designing PTG systems and researchers developing new tools for human-AI interaction design.