I was facing the same problem just a few days ago: I got a fully polished AliX case which felt quite good from a weight perspective, but was missing any brush strokes.
So, I was looking for a quick and cheap DIY way to introduce some straight brush finish.
What I ended up using was a combination of 400 and 600 grain sandpaper and then the secret ingredient: a matting sponge (?) which came together with my wedding ring
I also did the middle links of the bracelet in the same go to give the combination a more vintage look.
I had the feeling, that the result would have been the same with only the matting sponge