Depending on the kind of final finish you want I've used an orbital sander with an 80 grit pad. this levels the surface and leaves a burnished, but even look. If you desire a mirror finish, keep increasing the grit size up to 220 then 400. Then apply jewelers rouge to a buffer and polish away. It's worked for me, but can be time consuming.Does anyone know the best way to correct mismatch on aluminum. I have about up to a 0.01 step on my housings. I would like to avoid machining from the sides if possible. Other areas are just a shitty finish from vibration. I will be adding a touchup pass on those (top angled surfaces). Still I might need to disk them. I am wondering if there is special disks that won't load up made for aluminum.