Thanks Sprockets! For the help here, and for a bunch of other info in other topics.
Updated the gearbox dimensions. Thanks for catching that, it did look pretty amateurish.
Those are ribs on the housing. I haven’t had any courses that have even touched design for injection molding yet, so all injection molding projects were done on my own time during my design focused internship, and I don’t really have the knowledge to fix the filling issue. Can you recommend any reading?