When hovering the mouse pointer over a collection that can not be made due to missing items, the missing items are listed underneath the description.
It however does not clear the list when you hover over another collection, so the list grows longer.
I am missing 1 cauldron for the Endless Energy, but the pop-up says missing items:
Kettle - 8
Cauldron -1
Kettle - 8
Kettle - 8
Cauldron -1
Cauldron -1
Kettle - 8
Kettle - 8
Kettle - 8
and so on...