The intention of selling these raw aluminum parts is for those that are comfortable creating a surface finish they desire. A anodized version of this shell may be more suitable if you would rather not do any preparation. With these raw aluminum parts, I recommend one of two options:
Finishing the aluminum surface by cleaning and applying a coating. This is the biggest benefit of these housings as you can create a matte surface, or a mirror finish before a coating is applied. A matte surface can be accomplished quickly by using a 3M pad (ultra fine seems to work well). For polishing, there are many youtube videos on how to polish aluminum.
Allow the surfaces to show wear/scratches as is.
3. Please note that there has been a recent change to eliminate the IR port hole at the top.