Ability to queue up a spell when your spell factory is full
Just like the barracks, I think it'd be very beneficial to those who boost barracks and the spell factory. to be able to queue up at least one more spell than your factory can hold, so that like the barracks, it will create while you are off searching for a base.
So for example if you have a level 4 spell factory with no spells currently made you could queue up 5 spells..
Or if it was full with 4 spells already you could queue 1 up, so it's timer counts down while you are out in the clouds searching for a base.