I have designed a pan-tilt camera unit that can be mounted directly on the BlueROV2.

This design allows the pan-tilt functionality to be added without modifying the standard BlueROV2 enclosure, dome or camera board.
The unit consists of parts that can be 3D printed and several mechanical elements (purchased parts).
As some 3D printed parts require some precision, such as servo motor gears and bearing inserts, please modify the data to suit your own environment.