Painting MDF Cupboards

Having made S__t loads of MDF cupboards etc, have found the easiest and cheapest method is to make sure the cut or routed edges are well sanded .
Then use emulsion paint with a small roller, when dry lightly sand with fine sandpaper or wirewool tack of and repeat.
If using a gloss paint and white use Armstead water based, brilliant stuff , repainted all wood a year ago and still white, no discolouration .
Use a 2 to three inch paint brush well loaded to paint and then lightly roller for good finish, light sand and tack of and repaint, good gloss and durable if not up to oil based but no hassle repainting every 3 years.
Can all be done in a day if you so wish , good luck.