I don't know if everyone already knows this but I'll share anyways. For warm balance and negative green, as well as a ton of other custom WB, I came up with a homemade solution. I just went to home depot and picked up some of those large color swatch cards they have in the paint section. Just find the right colors. Then just loop em together. Voila, some portable white balance cards.
I know that doesn't exactly save much money, but hey...a buck's a buck!
I know that doesn't exactly save much money, but hey...a buck's a buck!