Migrating from a single Dockerfile to Bazel's rules_oci for container image building has significantly improved Plaid's CI speed, reducing median build times by half and shrinking images by 90%. The transition was made possible through careful planning, automation with Gazelle, and the use of ephemeral BUILD files. Key takeaways include choosing a remote cache provider, optimizing developer experience with BUILD file management, and avoiding common pitfalls such as running Gazelle on-save commands in IDEs. With Bazel's caching and strict dependency tracking, Plaid has streamlined its container image builds into a scalable system, meeting primary goals of faster CI and improved local development while uncovering opportunities for future improvements.