It may seem tedious, and it is a bit. But not nearly as much so as alot of people though. You can filter out Model Viewer by Weapon / Armor Type. Just cycle through all the models, and set up a transmogrify set you like. Each item has two ID numbers, I believe it's the second bracketed number that is the ID number.
Another way is stealing other peoples transmog sets, than adjusting them as you see fit. If you find models that are the same, but are different color. Go to WoWhead, find the item, and select the button that says something like Shares Model With... Or Same Appearance, Something along those lines.
It does take time to do, unless you cheat and use Wowhead transmog page that goes by Set (Not just PvP or Tier gear.)