I agree Gianni Agnelli was famous, among other things, for wearing his watch in a peculiar manner, but as far as I remember he did not have any custom-made cuffs (by the way, he was also famous for wearing standard off-the-peg Brooks Brothers shirts). He simply used to fasten the watch above the cuff, instead of on the skin under the cuff.
I may be wrong, but it should be fairly easy to find some photos to sort it out.
Cheers.

Fabrizio