Custom Furnace Slot Amount Issues [1.12.2]

[BloxBoss6]

I followed a tutorial off of youtube to build a custom furnace that has 2 inputs. I made 1 of the inputs be for casts and the other be for the metal to cast. I want to be able to set the amount of metal necessary for casting, but everything I have tried on my own has not worked. The furnace works in every other way, it just always takes only one item and won't wait until there is more than one item. Any help would be greatly appreciated.

 

All Files Used for Furnace

 

Edited September 10, 2020 by BloxBoss6