I was looking foward to DC’s cheapo B&W reprint series, Showcase Presents, getting to Metal Men, as I enjoyed a few issues as a kid back in the ’60s and had barely read any since. It’s actually rather less fun than I had anticipated, but one thing gave me great entertainment.

Basic  setup: Doc Magnus builds a half-dozen robots, made out of different elements, and with powers and personality vaguely derived from their composition, so Lead is dense in every sense, Mercury is both liquid and mercurial, Gold is noble and so on. Five of them are built in male shape, one, Platinum, in female. Obviously platinum doesn’t much imply a personality, but she had one: she was female. In those days, that was enough.
When they have to go on dangerous missions, Doc Magnus regularly decides that there is too much danger to expose a woman to, and tells her to stay behind. Obviously almost all sexism is kind of stupid, but extending it to one of your robots because it is built in a slightly different shape from the othersis really going above and beyond the call of duty (and she is clearly not the weakest or most fragile – Tin is in there for comedy relief (there is no suggestion of why he thought tin was a good metal to use), and Magnus never tries to stop him going).