If you want to do something like the article, with a custom layout (e.g. defining characters for Option and Shift+Option), then what you want (as hyperjeff ment

If you want to do something like the article, with a custom layout (e.g. defining characters for Option and Shift+Option), then what you want (as hyperjeff mentioned above) is Ukelele https://software.sil.org/ukelele/ https://software.sil.org/ukelele/