Luthor can create a variety of machinery at Remarkable level; it seems that this limitation only exists because of Luthor's obsession with defeating Superman.
Science * Mathematics * Economics
Electronics * Robotics
The Legion of Doom * A network of personal henchmen in the American underworld
The first time young Lex Luthor met Superboy, he saved the Teen of Steel's life by getting rid of a piece of Kryptonite which was killing Superboy.
Luthor was then a teenager himself, and he admired the hero of Smallville. So when his family moved there, the two became fast friends. Superboy even built a laboratory for Lex, who set out to find a cure for Kryptonite.
He had already done what no youth could have been expected to achieve -- he had created life in his lab! This protoplasm he made was to be the source for the antidote. But in his excitement, Luthor knocked over some chemicals, causing a lab fire.
Superboy blew out the fire, but his super-breath accidentally destroyed the protoplasm and the resultant fumes made Lex's hair fall out. Luthor blamed Superboy, claiming the Teen of Steel had done it because he envied Lex's genius. Superboy never got the antidote.
Young Luthor tried other inventions to make himself a great scientist, but when they failed, Luthor blamed Superboy, insisting he had ruined them. In time, Luthor turned criminal and was sent to a reformatory.
Lex's parents were horrified by their son's actions and disowned him. They left Smallville, changed their name to Thorul (an anagram of Luthor), and told their little daughter Lena that her brother had died in a mountain-climbing accident. Not long afterward, Mr. and Mrs. "Thorul" were killed in an auto accident, and Lena grew up not knowing that her brother was the notorious Lex Luthor.
Luthor continued to bedevil Superboy as they grew up. It was in the summer between Clark Kent's last two years of college that Luthor unwittingly did the world a great favor. Overcome by the death of a friend that he was unable to prevent, Superboy had gone into retirement. A challenge from Luthor brought him back into action.
Later, when Lois Lane was doing a feature article on New England witchcraft, she met a librarian named Lena Thorul and planned to mention her in the story -- complete with pictures. Luthor used his science in an attempt to scare Lois off the story. Superman discovered the truth, but he and Lois promised to keep the secret of Lena's true identity even from her.
Lena later moved to Midvale, met Supergirl, and finally married Jeff Colby, an FBI man who had once arrested Luthor!
Some time after, Luthor challenged Superman to a duel on a red-sun world, where the Man of Steel would have no powers. They discovered the people had slipped back from civilization to savagery. Lex began helping them, and they thought of him as a hero. He finally surrendered to Superman on the condition that his foe use his powers to send the water which that world needed.
The planet changed its name to Lexor, in Luthor's honor, and he married a young woman there, Ardora. He might have lived there as a hero, but he always returned to Earth to renew his feud with Superman.
Lena had a son, Val, and lost her husband. However, she did learn Lex was her brother.
Ardora also had a son, but soon after, Lex found and ancient battle-armor on Lexor, which seems to have caused erratic actions on his part. This led to the destruction of Lexor during a battle with Superman. Luthor blamed the Man of Might for the death of his wife and son. For a time, he had headquarters on a fragment of Lexor in the Atlantic, but Superman recently discovered it and arrested Lex there.