Plastic has been around a long time too .. these are aluminum foil core, so metallic looking and conducts electricity,
but of a non brittle plastic type wont dent or crack (unless sub 0C) from metal fatigue.

Got dosh to invest? the PDW Full Metal Fenders come in black anodized https://www.ridepdw.com/goods/fender...l-fenders-road

Berthoud Stainless steel ^^^ are spiffy too..