On my (unshaved) copy the "hood" look like it is part of the body. It extends all the way from the focusing ring...
True, I confirmed this by downloading a copy of 10.5mm service manual. The hood extends up to the MF ring.
But then, with a carefully balanced cut (approximately 3 mm above the golden ring), I was able to keep the four hood petals together. It is even possible to slip the hood back on for DX shooting.
Care must be taken not to lose it, as the front element slides inside the hood as you focus.
Anyway, the advantages brought by shaving the hood exceed the disadvantages.
For example, cleaning the front element, which is essential with fisheyes, is much simpler than with the unshaved lens.
Naturally, the big advantage is the ability to make a full circle shot in FX by combining two exposures, one taken in portrait mode and the other one in landscape.
Ok, another nerd task to cancel from the -long- todo list
The todo list has just been extended by one: I'm working on a symmetrical L-bracket which will enable to take two perfectly aligned shots, I need a portable solution; Seapy's beautiful accomplishment has the only defect of being hardly portable...
The key word here is symmetrical, that is the distances of the mounting rails from the optical axis of the lens should be equal.
Ciao from Massimo