[mauvehaus]

Or titanium[0]. Neat fact about anodizing titanium: the colors are the result of the thickness of the resulting oxide layer and how it refracts different wavelengths of light[1].

[0] https://www.snowpeak.com/collections/drinkware/products/tita... There are many. This is my favorite.

[1] https://chemistrytalk.org/titanium-anodizing/