It is easy to do and allows you to create a variety of nice finishes with little extra effort.
Step 1: Items Needed
Every aluminum box should be sanded before painting to remove the oxidized aluminum from the surface so that the paint can adhere better to the base metal.
For this type of brushed or buffed finish, I am using an abrasive wheel that mounts in a hand drill.
The red and gray wheels are similar but the latter is a finer mesh that produces a smoother finish. The material seems to be some sort of tough nylon woven fiber much like the 3M abrasive pads that are commonly available.
I bought these buffing wheels in a kit at Harbor Freight.
Step 2: Buffing the surface
Go over the entire surface of the box. Typically I start at one end and work my way to the bottom of the box face. Move the angled drill side-to-side and you will see a buffed and highlighted pattern emerge in the aluminum.
It is readily produced and if you make a mistake, all you have to do is buff over it to remove the error.
The sides of the box can be flat sanded or buffed with the abrasive disk to add some dimension.
Step 3: The pattern appears
It is important to buff the entire surface of the box to remove the oxidation.
Usually, I do the edges before starting on the face or sides of the box.