I know they have armor with hitpoints in their first iteration.

If you plan on having a house rule for armor getting damaged or absorbing damage then you might take a look at Hackmaster.

What exactly do you want this information for? I don't believe there's really a good method or table to go by in 3.0, 3.5 or Pathfinder. Most armors are in fact much thinner than one inch in thickness.

Since there are specific rules for sundering items, it would be nice to have official rules for this since (to my knowledge) armors and weapons have never been specifically stat'd for the 3.5 game. Also, for Padded armor, I was unsure how to categorize this, so I just stuck it into the leather category. Going by this table and assuming that each of these armors are 1' thick, I have put together the following, but as I mentioned above I'm not really sure this would be accurate. The problem I have encountered in trying to use the Substance Hardness and Hit Point table on pg 175, is that the Hit Points are calculated per inch, and I have no idea what the thickness is of the armors. Right now I need the hardness and hit points for all the armors. Does there exist somewhere, a breakdown of hardness and hit points for armor and weapons?

Dead space 3 hit points vs armor