After some time and effort, I have made mostly all weapons into .OBJ files so it can allow skin creators to have a better idea of whaty they are creating.

Inside Photoshop, place the .OBJ onto a blank canvas, Photoshop will then open the file, you can use the mouse tool to look at and rotate the model. To edit a texture, apply the .TGA file onto the model, a second tab will be created showing the texture you just applied, edit this texture. When you tab back into the 3D model, it will update in real time.

Discliamer

• These only will work with Photoshop cs6 Extended, Photoshop CC and a hand full of other programs, these files will not work with any other earlier version of photoshop to my knowledge.
  
• DO NOT ask me to tell you how to apply the texture to the model, use google if you need help.
  
  Link to Google Drive: https://drive.google.com/folderview?id=0B5JySfNcpNvQd3pqV0M5ZmR5NTQ&usp=sharing
  
  Here, I finally made a guide after one and a half years lmao: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=844825568