While thinking up my Email Followup System, I considered the need to duplicate Gmail drafts. I also wanted to build a Gmail extension involving cards because I had never done.
I got inspiration from Amit Agarwal at his Digital Inspiration blog by reading the article: How to Copy Draft Emails in Gmail. However, his system only allows you to replicate 3 emails at a time for free. I wanted the ability to create 77 copies of a Gmail draft on the click of a button. So I got to work. Eventually, I built it using Google Apps Script and make a YouTube video about it.