On my hunter, I have a transmog set that looks like plate. Not so coincidentally, it happens to be my pet-tanking set.
The base components of this set are from the "Knight's" set:
The true gems are from other sets however:
Ornate Pauldrons (shown) though if you want a softer look, the Ancient Pauldrons are nice.
Now come your accessories and trimline:
Ranged - Wolfslayer Sniper Rifle (shown) though Rifle of the Platinum Guard is a very close second.
Tabard - Stormpike Battle Tabard (shown)
Shirt - White Tuxedo Shirt (shown). The shirt does show through in many places.
Bracer - Any bracer. Color can show as a short banded cuff above the gloves.