Almost Apple products utilize aluminum for enclosure, from iPod, iPhone, iMac, MacBook, and it's become an identity for apple products.

Apple has patents processing aluminum for its case, see here

While choosing the right material for enclosure is one thing, the finish is another thing, even more important,  Coyres keyboard enclosure has gone anodization and sandblasting processes.  

What is anodization?

Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized.

The anodic oxide structure originates from the aluminum substrate and is composed entirely of aluminum oxide. This aluminum oxide is not applied to the surface like paint or plating, but is fully integrated with the underlying aluminum substrate, so it cannot chip or peel. It has a highly ordered, porous structure that allows for secondary processes such as coloring and sealing.

Coyres keyboard has the enclosure color anodized.

see more details by Aluminum Anodizers' Council

What is sandblasting?

Sandblasting is process of smoothing and cleaning a hard surface by forcing solid particles across that surface at high speeds using compressed air. There are two kinds of sandblasters: “Suction” / “Siphon”" & “Pressure” Blast Systems. There are two basic kinds of sand blasters: Blast Cabinets & Portable Blasters.

See Princeton University's More info

After anodization, the Coyres keyboard enclosure is sandblasted.

After these processes, the keyboard does look Apple and feel Apple.