Add a $10 walmart box fan and a furnace filter to the box and you will get a pretty efficient spray booth (water based paint only). I find that with some of the inexpensive paints such as folk art you can use them right out of the bottle with 40#s or more pressure.
One of those large plastic tubs. Springs on each side about 6inches in. Small screw hooks on each end of the plug attached between the springs. You can turn the plug any angle ya want as ya spray.