How do you extract the models

So I just got OG Doom 3 on Steam today and I tried the main game and it was fun. I also did a little multiplayer but back to topic. I was wondering how I could get the models from the game Specifically The BFG9000 View Model and world model. Does anyone know how to extract them and if you do could you tell me 

pk3 files are basically zip files. You can open them with 7zip or other zip tools.