I spray in my 2-car garage, which is also my workshop. I have an old window fan (mounted on casters) which I roll into one of the 2 single garage door openings. I close the door down onto the top of the fan, and I have a light-weight 1/4" ply panel which closes the opening to the side of the fan. With the other garage door closed the fan is in the only open space. The fan pulls air out of the garage. I open either a pull down attic stair to supply air in from the attic, or open the door into house and a window nearest that door for supply air thru house. Choice here is determined by temperature in attic, house, and outside. I can somewhat control the air flow thru the shop by how much I open the door, window, or attic stair. The model I am spraying is between me and the fan, and the model is 3~4 feet from the fan, such than the fan pulls spray fumes away from me and exhaust them out thru the garage door opening. If I am using airbrush I dont need a mask and never even smell any fumes. If using anything larger than an airbrush I use a mask, again I never smell any fumes. Spraying the clear coats with full size gun puts the most amount of overspray into the air and when I spray that, in addition to the mask I always wear long sleeve shirt and one of those cloth pull over head covers, even if its hot and it makes me sweat... The fan has about a 3-foot diameter blade and I feel like it does a complete change of the air volume in the shop at least once every minute, probably more...
I managed to find a couple of old pictures that show the window fan in action.. Check out the holders I came up with for the flaps and elevator. I use some plastic strips sized to fit into the hinge slots for the mounting of parts. The jig holds the part at a 45° which is perfect for spraying the first side, then you flip it over to spray the other side without having to touch the part..