The Minnesota Library Publishing Project (coordinated by Minitex and Minnesota Libraries) brings Minnesota library users Pressbooks online authoring and publishing tool.
To get started
MLPP Quick Guide - How to Create a Book
OER materials are, by definition, licensed for others to freely use and re-purpose (the license may still require attribution).
OER follow much of the same workflow as a traditionally published resource. Consider the following workflow from Open-NYS: