Forking is a primary way provided on PHPSandbox to share notebooks. It allows you to have a copy of any notebook on PHPSandbox.
By default, all notebooks on PHPSandbox can be forked. In simple terms, forking a notebook is making a copy of the entire notebook code without its secrets. Secrets here, includes environment variables added by the original owner of the notebook.
You can fork notebooks (yours or someone else's) from the top bar on the notebook page using the Fork button. You will see the fork button appears on ALL notebooks on PHPSandbox. If the notebook is yours, you will be required to confirm if you want to fork your own notebook.
While a forked notebook will have a copy of the contents of the original notebook, the settings and Environment variables values are not copied over to forked notebooks.