I know about two composite materials -- particle board and composite leather. Each is made of small bits of the original mixed with filler/binder. In halacha, there are times when wood and leather are named as specific needs:
A prohibition against leather shoes on Y"K and T"B'av (ignoring for the moment all the opinions that argue on this)
Would these laws apply to the composite version of wood and leather? Each is made of the original but is not identical with the original.
n.b. there might be other composites which could stand in for materials listed in halacha - this is not meant to be an exhaustive list, just the ones I have come across recently.