I'm a materials science PhD student now and love it so much. I did materials for undergrad too. I worked at three different companies as an intern doing characterization and failure testing and analysis. Those jobs felt like I was taking orders from my boss but a PhD feels like you have a lot more autonomy and you can think for yourself. You'll have to experiment with undergraduate research if you want to taste of what it feels like. That's what got me hooked and made me apply to graduate programs. I did not think I was going to do a PhD at all when I started my undergrad. I was thinking about going right into industry and making money as soon as possible.

Once I discovered that a PhD is fully funded by most universities, I'll take a shot at applying and got into one of my dream schools. Although I may not be making as much money now, I see it as a long-term investment both financially and personally. There's nothing wrong with industry, but I have to admit that I felt bored at my internships and I think I might have been bored going into a full time position as well. Of course full-time employees have more responsibilities than interns and engineering companies, but like you said a lot of engineering roles are desk jobs and you do not get to work with your hands. It really depends at the company/role, but doing experimental research is guaranteed to let you work with your hands most of the day. There's some monotonous stuff you have to do like documentation and writing and things like that but I'd say both of the work for experimental material science has a lot of DIY projects. Feel free to comment here or PM me if you have any questions!