Are there any open source Packer build configurations or anything else that can be used to reproduce the base boxes from scratch? I wouldn't usually run a base

Are there any open source Packer build configurations or anything else that can be used to reproduce the base boxes from scratch? I wouldn't usually run a base box that I can't also see/use the automated build scripts for. For my own boxes (e.g. https://github.com/geerlingguy/packer-ubuntu-1604 https://github.com/geerlingguy/packer-ubuntu-1604), I make sure to prominently link to Packer configs licensed under the MIT license (based on Chef's Bento project (https://github.com/chef/bento) https://github.com/chef/bento)).