So I am working on getting an upgrade slot into a custom furnace of mine. I have a recipe that functions the way I want, but when I try to get an upgrade slot where you can put an item that speeds up the time it takes to make an item smelt (similar principle to a speed upgrade from Extra Utilities where you have a slot that changes a function), I either cannot access the GUI at all or the recipe doesn't work. I am wondering if anyone who was successful at making an item upgrade for their furnace would be willing to share their code with me.
