> Do you know if such cable exists?
> It could be for Nikon or Canon.
> I guess that this must be a homemade cable, am I right?
No, if you are talking about Canon point-and-shoot cameras .. which I doubt.
At present, one SDM user has 30 cameras linked another has 52 cameras linked, both for "bullet-time" sequences.
Thay are synchronised to typically 1/5000 sec.
Peter Murphy has a nine-camera rig.
You can use this USB remote switch and USB extenders :-
(declaration of interest: I have a free, prototype unit)