Aluminum Cosmetic Finishing Methods
If you purchased an unfinished Game Boy cartridge or possibly a shell from Boxypixel.com, see below for some basic methods to cosmetically finish my machined Game Boy parts.
The machined shells are now all raw aluminum, and come with some very fine machining marks. Due to the nature of raw aluminum, they can be scratched so take care with the exterior finish. The good news is, even if you do get scratches, the scratches can be removed.
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Once you get the finish to the level of shine you prefer, I'd recommend using a product called protectaclear. It's not cheap but does an excellent job of protecting the exterior and will not yellow as some clear paints would.
Before doing any polishing, ensure there are not ANY loose metal shavings or burrs on the parts. You could accidentally scrape the metal shaving across the surface and create a scratch.
Next, simply use a microfiber or other non-abrasive cloth and rub the mothers in in. A little goes a long way here, and will require more cleanup if you use too much. It should start to turn black. Wipe off to see the shine.
The finishing process simply involves sanding the surface with progressively finer grits to get the surface to your liking. I find it best to start with 3M sanding pads that come in a few grits and conform well to small surface features. Below is a short video showing the first step to sanding the exterior.
From there, you can continue the same process with finer grits until the surface is as reflective as you'd like. You can get a mirror finish with enough patience and effort. Personally, this first step looks great alone in my opinion as it gives a sheen, with a very slight matte finish.
After the surface is to your liking, I'd advise protecting it from oxidation. Some simply use clearcoat paint, however this can yellow over time and is not very durable. I have found that if you cannot anodize (typically they charge $120), then use a product called Protectaclear.