I have been asked to make a metallic gold 3 tier wedding cake (10", 8", & 6") and have no idea how to calculate how much luster dust I will need to order ( as there is no supplier within hundreds of miles of where I live. )  Can anyone with experience of completely covering cakes with luster dust give me any idea of either calculating how much I might need, or of how much you used to cover a cake (& what size cake it was)?  Any input is greatly appreciated. 

Mixed with something like Vodka and painted on you should be able to cover those sizes with 2 of the little pots.  If dry brushing on maybe one more .  Better to have too much then run out.  It lasts for ever so any leftover can be use in the future. 

Forgot to mention dry brushing will give a much lighter but nice color whereas painting will give a much more matalic look.

Thanks kakeladi  That gives me a general idea of how much to order.