Ya' know what? I never really paid much attention to the build 'cos it was either on my head mostly, in front of my camera, or on someone else's head. I don't recall feeling anything plasticky however I could take a 2nd look tomorrow. As I was unfamiliar with the LCDs in general, I'd have to say purely based on feel, I do not recall feeling it heavier than the LCD-3's or LCD-2's. If they are, I didn't notice it.
Checked about the frame around the cups, wooden (painted?) black.