The lightening pattern looks fine, if a bit conservative. Is there a reason the gearbox profile is a square? If you mess with the profile a bit and get it to fit closer to the internals, you could save more weight and get rid of the tiny lightening holes on the sides. One way to do this is to extend the CIM mounting screws and also have them hold the gearbox together, getting rid of the corner bolts and a good chunk of metal on the plate.
Your output shaft looks a little bit long. Are you planning on making this gearbox part of a larger drivetrain design? Or is this a just for fun thing?
