There is a weird fitting in the lid of the vulcanoid case I just got; it is a small, thick disk about 1" in diameter, with a 1/4-20 hole in the middle. The disk is rivited into the lid, and I cannot figure out what you are supposed to use it for.

Unless it is for a tripod head? Did the wooden Graphic tripods disassemble for storage? That would explain the odd compartment in the front of the case, with a full-width wooden bar supported by canvas straps at the ends. I can see the legs going into the front of the case, with the head stowing in the lid. Although since the case is only 18" wide, the tripod would be rather short even with three sections.

Yup, the fitting is for the head and the compartment is for the legs. I think there is another recent post on this subject, somewhere.