Attendance wasn't really mandatory but he doesn't post his notes online. So the only way to get the lecture material is to either attend or get it from someone who attends class. Some aspects of the course were pretty interesting and I enjoyed it. He doesn't give a bunch of homework but he does make sure that he and the TAs are always available to answer your questions.

Crystal structures, atomic packing factor, line and plane directions, grains, phase diagrams, stress-strain curves

Professor was great! He was really passionate and knew the material thoroughly. He tries to make the class feel like a high school one.

If you plan on skipping a lot, take a different professor. This professor makes an effort to memorize everyone's names and will randomly call on people during class. He'll even have a 1 on 1 convo with you if you skip enough.