Phineas Mason, the reclusive scientist and engineer known throughout the criminal underworld as the Tinkerer, once worked at Oscorp Industries as one of their top employees until he was discovered to have been using his patented-surveillance technology to spy on and steal government secrets for the highest bidder. Since the company's owner Norman Osborn didn't want to have any of his own criminal activities exposed at the time from Phineas' scheming, he had him fired from the company and any bit of his tech patents removed from the records as well. Down but not out, Mason soon set up work in the criminal underworld as a rogue engineer for hire, modifying and building technology or weapons for criminal buyers to use in their heists. One of his best customers so far has been Wilson Fisk the Kingpin, whose underlings have come to Mason to have their own weaponry and armors built for a pretty price.
Lately, with the fall of most of HYDRA's high-ranking faction leaders, Mason has started to collect most of their confiscated developed tech and repurpose it for his designs to the highest bidder, with the most-often used ingredient in his weapons being Chitauri metal and energy core reactors.