Jim Mueller wrote in
eb.com:

You can make it look better by using a fine wire brush on it; most easily
done with a wire wheel in a grinder.

I didn't think of that.. I've done something like it with small laser cases
built in extruded 1 inch square tube though, using emery paper glued to a
flat MDF board. It's a very nice finish, but it's not a method for large
parts, too much work. I used to get numbness from gripping sharp edges under
high pressure, and that never entirely healed. It was worth it at the time,
but no-one could make a lot of them that way unless they wanted permanent
injury. I did try one wire brush at the time, but for whatever reason it
failed, I couldn't get consisteny the way I could with the emery board. That
brush was only good for derusting steel before painting with hammerite. Maybe
a larger and faster one, used lightly, might have worked better, but not on
small parts I think (would have damaged the fine edges).