Man spraying a vehicle with a 3" Spray pattern?
You really need a 6-12" pattern to get good results.
It helps eliminate runs & sags, Plus it lays the recomended Mill thickness.
I wouldnt use it to spray color( unless you can screw out the fan adjustment to get a wider fan pattern), definiately purchase
a good gun( HVLP or LVLP ) for color and clears , your results will be better for sure.
HVLP= High Volume Low Pressure
LVLP= Low Volume Low Pressure
These guns have excellent Paint transfer
meaning: More goes on the vehicle then in the air.

Race Willy
I have a Thread here in the paint area about guns
do a search on my name and look for Paint Guns.
It may be of help for you and your son.

SprayTech