Ron DeMarino was a New York based guitar player, builder and repairer. An early brush with John D'Angelico inspired DeMarino to try building guitars and he opened his own shop in the late 1960s. DeMarino is best known for working on Lennon's guitars but he also made custom order electric guitars and basses. The DeMarino Guitars business was carried on by his son Steve.

Source: Pieces of John Lennon’s Guitar Up for Auction. NY Times, November 10, 2014