[cableguymn]

I thought it was stainless..

and that is worse than aluminum.

[woodbutcher1963]

I could be wrong, but I think that is what I remember from a YouTube video I saw a few months back.

Musk had an Italian company build a casting machine so they could cast the frame in 1 or 2 pieces. The model Y made in China is cast in one piece. That is how they can assemble them so fast.