A modular spray apparatus, comprising: a handle module including a first housing having an inlet adapted to be coupled to a source of pressurized gas, a flow passage extending between the inlet and an outlet, and a first coupling member proximate the outlet; and a head module including a second housing having a second coupling member removably coupled to the first coupling member of the first housing, the second housing including a first intake port adapted to be coupled to a source of liquid material, a second intake port fluidly communicating with the outlet of the handle module, a mixing passage fluidly communicating with the first and second intake ports (134, 138) and having a spray outlet, the head module further including an air cap coupled to the second housing and disposed about the spray outlet, a nozzle fluidly communicating with the spray outlet, and a needle assembly operatively coupled to the second housing and operatively associated with the nozzle to control a flow of liquid material and pressurized gas emanating from the head module, the handle module further including a trigger movably coupled to the first housing, the needle assembly being removably coupled to the trigger, characterized in that the first coupling member of the handle module and the second coupling member of the head module are operative to be de-coupled from each other without disassembly of the head module, the needle assembly remaining with the head module as a unit. a handle module including a first housing having an inlet adapted to be coupled to a source of pressurized gas, a flow passage extending between the inlet and an outlet, and a first coupling member proximate the outlet; and a head module including a second housing having a second coupling member removably coupled to the first coupling member of the first housing, the second housing including a first intake port adapted to be coupled to a source of liquid material, a second intake port fluidly communicating with the outlet of the handle module, a mixing passage fluidly communicating with the first and second intake ports (134, 138) and having a spray outlet, a first intake port adapted to be coupled to a source of liquid material, a second intake port fluidly communicating with the outlet of the handle module, a mixing passage fluidly communicating with the first and second intake ports (134, 138) and having a spray outlet, the head module further including an air cap coupled to the second housing and disposed about the spray outlet, a nozzle fluidly communicating with the spray outlet, and a needle assembly operatively coupled to the second housing and operatively associated with the nozzle to control a flow of liquid material and pressurized gas emanating from the head module, an air cap coupled to the second housing and disposed about the spray outlet, a nozzle fluidly communicating with the spray outlet, and a needle assembly operatively coupled to the second housing and operatively associated with the nozzle to control a flow of liquid material and pressurized gas emanating from the head module, the handle module further including a trigger movably coupled to the first housing, the needle assembly being removably coupled to the trigger,