Comment by refurb

I did something similar with drawer handles. I was living in a place with cheap furniture and the handles were aluminum billet cut to length and tapped so it could be screwed to the drawer face. The edge on either side were crazy sharp. If you bumped it with your knee you'd easily cut the skin.

So I took some 1000 grit sand paper for metal and gently wet sanded the edge. If you rotate it a little you can get a very small radius evenly around the edge and it will keep a nice finish that matches brushed aluminum.

I'd actually feel comfortable doing this to a Macbook having done it to the drawer handles. Just use little pressure, back the paper with something flat, and check your progress often. It takes very little to remove the sharpness to the edge, to the point it's hard to see with the naked eye.