It can save you from pink and black textures when skinning!
This tutorial can save you from pink and black textures for weapons when trying to skin a different weapon. This will also allow you to edit the model and materials files at your liking using the Left 4 Dead .vpk method. Anyways onto the tutorial!
1. Download GCFScape and save it somewhere on your computer
2. Open up GCFScape (x64 if you have 64-bit windows or x86 if you have 32-bit windows)
3. On the top menu click on File>Open and then browse to STEAM DIRECTORY/steamapps/common/Counter-Strike Global Offensive/csgo
4. Open the file named pak01_dir.vpk
5. In the main screen of GCFScape select materials and models - Hold ctrl and click on both of them
6. Right click materials or models (doesn't matter which as long as both remain selected) and choose extract
7. In the window that pops up browse to: STEAM DIRECTORY/steamapps/common/Counter-Strike Global Offensive/csgo and hit ok
This will now go through and extract all the models and materials to your cs:go directory. After that is done, you can use VTFEdit to open the textures and extract them to edit in your favorite photo editor.