Awe, you are mistaken sir. This is a TFmaster custom. I don't know if I could make an Alternators custom look this good.
I can still answer some of your question though. I believe that TFmaster made the door removable. In the close-up picture of his shoulder you can see that there is still space at the top of the pin holding the door to his shoulder. If he doesn't explain here I'll just ask him personally.