I saw that multicamera synchronization was released for D415 a couple months back, and at the time there wasn't a timeline for when this feature would be released for D435. Is there any update now?
Due to a delay whilst waiting for the firmware to have sync code added before sync could function, the sync feature was only released for D415 very recently. There is still no information on when sync will be available for D435.
I do not know of any place where a pre-made sync cable can be purchased. You would need to obtain the parts yourself using the part references in the multiple camera paper and assemble it.
