Excel and PowerPoint custom ribbon

This code should work as is for both Excel 365 and PowerPoint 365.

Replace the files Excel.officeUI and PowerPoint.officeUI in the directory C:\Users\dave\AppData\Local\Microsoft\Office which is usually a hidden directory.

Much more related guidance at

https://stackoverflow.com/questions/8850836/how-to-add-a-custom-ribbon-tab-using-vba