Thanks for taking the class! I hope you now have some more buttonhole “tools” in your Knitting Toolbox.
Here are some other resources you might find helpful, including affiliate links:
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.
TechKnitter has a series of articles on buttonholes.
The Improved Eyelet Buttonhole from A Pile of Sheep is described here.
The Tulip Buttonhole from TechKnitter as demonstrated on YouTube by Eunny Jang. I haven’t used this one in “real life” yet, and it’s a bit fiddly, so it didn’t make it into class. It’s worth a try.