i’ll take 3. we can be boring together

I strongly suspect 3 is correct - removing material from the corners might weaken the structure.

I would use a CNC machine to round them more precisely and uniformly though.

You probably don't know much about filing, but there is no reason it would be any less accurate than CNC if done properly.

Also doubt this would affect strength, given the apparent thickness behind it, really depends on the interior, which is almost certainly also rounded for strength, and to prevent a week point for cracks to start.

Haha I was thinking the same when I read he hand filed it

As it is with any box, there is only so much material you can remove from the corners before it disintegrates into disconnected surfaces.

Filing vs. CNC doesn't make one bit of difference.

With a CNC you can make sure you'll get a uniform curvature.

You can get uniform curvature when filing. Ever hear of filing buttons? Or checking your work with a radius tool until you are in compliance? Stop talking about what filing can't do if you don't know anything about filing.

I have just the opposite reaction.

I'd be looking for another job altogether.

Really? Co-worker 4 is just repeating a pun. Using "sharpe" to mix the meanings of "good looking" and "literally sharpe" is a well known joke. Almost a dad-joke, a joke that's been done so many times that everyone recognizes when it's there to be done, but the person who actually does it out loud will annoy people with their predictability.

1 and 3 are way more creative.