You may want to look into using an Iwata LPH50 spray gun. They use only 1.8 cfm (at 13 psi) with the 1.00mm nozzle yielding a 3.9 inch pattern width or 2.1 cfm (at 14 psi) with a the 1.2mm nozzle yielding a 5.5 inch pattern width. It’s the world’s most efficient spray gun. Its a low volume/low pressure (LVLP) spray gun and it produces just about no overspray whatsoever. The spray gun uses one of 4 paint cups ranging from 130mL (4.4 oz) to 400mL (13.5 oz). Best of all... it incorporates a gravity-fed, side cup design that’ll give you an unobstructed view of whatever it is you’re painting.