Just the other day he posted about how they were able to modify the one member of the family identified in their paper which is not an aperiodic monotile into one that tiles without reflections.
+1 csk is as good as it gets. Had him for my first CS class there and to the end of my time there, that class stood out both in terms of quality and enjoyment/engagement.
If you're at Waterloo and have the chance to be in Craig's class, jump at it.