Some of the old Casios were steel such as the H101 Marlin, though a lot of them were base metal with chrome plating.
They switched to resin with chrome plating which did away with the pitting issues that the base metal watches developed. But they lacked a certain character.
Now things have turned full circle and Casio have again started selling stainless steel digitals. It started with the G-Shocks, but now with the A1000D-7EF they have a normal digital with a stainless steel case for £90.