> Copper is the rarest material used in major applications, but this is relatively less total mass consumed than rebar. At 43:51 in the video, he claims that a

> Copper is the rarest material used in major applications, but this is relatively less total mass consumed than rebar. At 43:51 in the video, he claims that an outer layer of stainless steel rebar is sufficient to protect the interior, so the goal is not 100% stainless. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth... says chromium is slightly more abundant than copper.