Ohhh this aint styrene Steve! Both the boom & stick are a couple of pounds each (I don't have a scale to measure). That's 5mm steel you see within, I don't know what the material is that is formed around the steel for it's detailed shape.

Obviously any sort of impact to it will chip it.
Ole weighed in his rtr 870 model @78lbs. I'm gonna have to build a skid to slide the 850 down the stairs to the quarry.