I worked construction roofing and machine shops and my handwritting is far worst but in those feilds a pencil and paper is hard to find.
That's an interesting thing. I'm not attacking you personally, it just seems to be a common comment from a lot of people who work in some type of construction or manufacturing today. My father worked construction in some fashion for 50+ years and you would
never see him without a pencil and a paper pad. At the "bottom" when he was making dinner tables all the way up to when he became a foreman working in Hollywood (at one point overseeing maintainence on the Hollywood landmark) every photo of him shows him with a pencil (or pen) located somewhere on his body.
I suppose it's the cost. When Home Depot started charging fifty cents per pencil, people kind of lost interest or something.

In any case, back on topic.
In wood construction, you can purchase a "square" drill bit to cut more or less square holes in wood. One type is a square mortise drill bit (my preference) or a Reuleaux drill bit (requires a special drill) to drill relatively square holes that can be easily cleaned up. Isn't there any equalivent in metal working?
From looking at the pictures, isn't the controller port a circle with a flattened top?