I am new to airbrush technique. I have a cake that is due in a week and I am going to airbrush whole cake instead of dye fondant. I wonder how long it takes for airbrush paint to dry on MMF? How much paint needed to cover 12 inches round cake (4 inches height)? Thanks!

If you have a bottle of airbrush colour, you'll have plenty to do the whole cake. Make sure you practice before you actually work on the cake. It would be best to roll out a piece of the MMF you're using on the cake and try working on that. You can then figure out how many coats you will need to get the effect you want.

Just make sure you build the colour up slowly, rather than doing one heavy coat which may run or go blotchy.

once its airbrushed do not put it in the fridge. It will take a few capfuls of colour to cover the whole cake, and do it in layers, avoid going back and forth as youll get darker areas at the ends, where you change direction.