I use a Grizzly Tools spray gun that costs about $40. After each coat, I clean by spraying laquer thinner and wiping all ports and surfaces with laquer thinner as well. In addition, I use paint filters to strain the material into the gun. In between coats, I store the epoxy in the fridge. To maintain a proper viscosity, I add thinner if the finish is stored more than a day between coats.
My guns will last for about 20 uses 3-4 bows at a time before I have to replace.