Just to follow up on my own question (though I appreciate the siblings): I found this article with some overview and example command lines: https://www.docker.

Just to follow up on my own question (though I appreciate the siblings): I found this article with some overview and example command lines: https://www.docker.com/blog/multi-arch-images/ https://www.docker.com/blog/multi-arch-images/ . As best I can tell, you don't actually need a custom builder. You can just skip the `docker buildx create` and go straight to `docker buildx build` after one workaround below. I needed the workaround from this comment to make it work (to install qemu? not sure): https://github.com/docker/buildx/issues/495#issuecomment-754688157 https://github.com/docker/buildx/issues/495#issuecomment-754... Overall a very slick experience for going from zero to multiarch containers. Well done, Docker.