An improved apparatus for generating a powder stream to be applied to a work piece (22) includes a powder reservoir (12), a mixing chamber (14), a powder metering valve (36,38), a transfer conduit (16), and a nozzle (18). The metering valve allows control of the powder flow from the reservoir into the mixing chamber where it is dispersed with and entrained in an air flow entering the chamber through an aspirating inlet (30). The air entrained powder is then conveyed from the mixing chamber via the transfer conduit to the nozzle. The nozzle includes a controllable gas flow input (43) and a powder stream generating passageway (42) configured and associated with the transfer conduit to generate a reduced pressure in the conduit and mixing chamber which draws the air borne powder from the chamber into the nozzle. One or more of the individual components are adjustable to control the size, configuration, thickness or other parameters of the coating on the work piece as a result of the applied powder stream.