Block-based programming languages can support novice programmers through features such as simplified code syntax and user-friendly libraries. However, most block-based programming languages are highly visual, which makes them inaccessible to blind and visually impaired students. To address the inaccessibility of block-based languages, we introduce StoryBlocks, a tangible block-based game that enables blind programmers to learn basic programming concepts by creating audio stories. In this paper, we document the design of StoryBlocks and report on a series of design activities with groups of teachers, Braille experts, and students. Participants in our design sessions worked together to create accessible stories, and their feedback offers insights for the future development of accessible, tangible programming tools.