Since you're using 1.12, sort of. Right now the Mass Fabricator will only work when given scrap, but it will take 1M EU to produce UU (ie the scrap has no bonus multiplier) and produces solid UU. It also has no recipe, nor does the UU Assembly Bench which is designed to turn the solid UU into useful things. So if you wanted you could add your own recipe for it, a recipe to convert solid UU into liquid and then just drop the energy requirement in the config for UU down to 1/6. The Matter Fabricator doesn't have any option for scrap only operation.
How do you actually do this? I could use some help figuring it out