Universal plasma spray extension gun systems and devices for thermal spraying of machine components are disclosed. In one embodiment, a plasma gun extension system includes: a plasma extension arm; an arm connector disposed on the plasma extension arm and configured to connect to an adjustable plasma spray gun apparatus; an arm coupler disposed on the plasma extension arm and configured to connect the plasma extension arm to a robotic arm; and a set of feed conduits disposed on the plasma extension arm between the arm coupler and the arm connector, the set of feed conduits configured to supply a flow to the adjustable plasma spray gun apparatus.