Primitive Crafting allows you to craft simple items within your inventory just by hovering over them with the materials. By default the mod only allows crafting between two items like torches and flint. All you need to do is hover one item over its other ingredient and hold shift for crafting options.
It really makes for quick crafting especially if you’re out away from shelter or just need an item in a pinch.
But there is a config option to allow crafting recipes with multiple ingredients that really expands this mod. So more complicated items can be pieced together in one click!