Usually we consider robots to have parts like servos, motors, gears and wires but the metal men seem to have none of that. They are basically AIs/robot brains Doc Magnus build and put in a metal shell that manipulates and shapes the metal at a molecular level.
Also has DC ever explained how Magnus was able to get enough gold and platinum to create his robots? Lead, iron, mercury and tin are cheap metals to buy but even if he was wealthy making a solid life-size male and female figure of gold and platinum would would be expensive. I'd like to imagine that Magnus started off making much smaller versions of Gold and Platinum and then have them roam around abandoned gold and platinum mines (or searching through junkyards for electronic parts) having them search for and add to their mass until they reach a certain size.