Mike Kasberg created a custom Casio-style watch face for the $27 PineTime smartwatch, which runs open-source InfiniTime firmware. He cloned the InfiniSim repository, including its InfiniTime submodule, and used OpenCode with Kimi K3, K2.6, DeepSeek v4 Pro, and DeepSeek v4 Flash models for most of the development work on Ubuntu. The models used an existing InfiniTime watch face as a starting point and produced an initial approximation from a reference image, but its text sizing and layout overlapped and was unreadable. Kasberg refined the design through specific feedback and isolated tasks, correcting individual interface elements. He then used a full-screen 240-by-240-pixel background image for static graphics while coding only the dynamic parts of the display. The prototype worked in the simulator and on physical hardware, but the PineTime’s constraints affected performance. Bluetooth transfer of the background image during installation took about 10 minutes, and swiping to refresh the full display takes one to two seconds because the watch streams the image from its file system rather than retaining it fully in memory. Kasberg published the code on GitHub along with an AGENTS.md file containing development notes and setup guidance.