Every Type of Plastic Used By LEGO

Neat! This is a very comprehensive writeup! I found this part particularly interesting:

Modern Technic bricks with pins, such as 42929, are dual-molded so the brick part is ABS and the pin is PA (this is why they show up in BrickSet as “multicombination”, even though it’s the same color throughout).

I didn't know dual-molding was possible, and I've never noticed a visible seam or difference in colouration.

I never put much thought into how many different plastics lego used

That's super neat, I knew some Legos were mad out of an ABS but not exotic materials such as POM