Copper/Bronze Fous?

Unless all the Servants you use are maxed already, fous are best used at low level to minimize QP cost. Still, the bronze fous have uses. Later, when the max Fou is 2000 instead of 990, you can use the bronze ones to go from 990 to 1000 without wasting the extra (anything past 1000 will be rounded down). From there, we will need the new 4* gold fous to reach the new 2000 limit.

If you're willing to work on it, save one HP Fou and one ATK Fou for each servant you use. Though if NA will follow what JP did, we will all get a free ATK and HP Fou for each Servant at 990.