Leucippus (450?-370? BC), was a Greek philosopher. He proposed the atomic theory of matter, that all matter is constituted of identical indivisible particles called atoms. This theory was further developed by his student, Democritus.
Is an example of a non-question. What about Democritus and his mentor Leucippus do you want to know?
Virtually all things are made with atoms, so you answered your own question. But there are some inventions that were accually made using the idea of Leuccipus' and Demorcrius' idea of atoms.