how do i make the astroforge functional?

me and my friend are working on a mod. in the mod, there is a crafting station that has 8 colored input slots and 1 black output slot in the middle. our plan is to let you put items in any of the 8 input slots and an item be fabricated from the output slot. for example, a fire, plant, ice and wind elemental metal can be put in any of the 8 slots and an alloy can appear from the black slot.

image link: https://imgur.com/gallery/astroforge-NTFHG3N