Thanks for taking the class! I hope you now have some more buttonhole “tools” in your Crochet Toolbox.
Here are some other resources you might find helpful:
The Simflex Expanding Sewing Gauge is the nifty tool I had in class. That link is to the best price I could find at the time, but you might poke around Amazon to make sure you find the best price.
Alternatives to buttons for shawls include the:
Jul Designs shawl pins and fastenings
If you want to make your own buttons, Google “crocheted buttons” or “Dorset buttons”, or make your own Fimo clay buttons. CGOA Hall of Famer Nancy Nehring even wrote a book on Dorset buttons.