Keith Kenyon was a political dissident and scientist who discovered a sunken gold chest that enabled him to modify its properties to become an elixir which he drank, turning him into the criminal known as Goldface. Using gold armor and a liquid gold spray gun, Kenyon faced Earth-One's Green Lantern on a few occasions. He eventually moved from Coast City to Central City and made a foe of its hero, the Flash... then retired.
Eric Knowles was a disgruntled toy maker who developed a tin armor and equipment incorporated as weaponry in the form of children's playthings. As the Tin Soldier, Knowles became an adversary of Earth-Two's Green Lantern before being decisively defeated.
Two other toy-themed villains who ran in the same circles as the Green Lanterns were the Puppet-Masters of both Earths. The Earth-One version faced Lantern then Robin's New Teen Titans while the Earth-Two version was an opponent of Lantern's fellow Gothamites, Batman and Robin.