Bed side gas filler door

[CheyLadd]

This is probably a stupid question but my truck has one of those screw in filler doors to access my saddle tank. (Yes, they cut a big hole in my bedside) I have finally hooked up my tank and am using it but I have to unscrew the door hinge to access the fuel cap because it is old, beat up, and I have no key to the door part. Does anyone know where you can get these door setups?

I would really like to make it a more solid billet type if possible but I cannot find one anywhere. I have done many searches but am not getting the right word combination. Any ideas?