In one embodiment, a method for processing carbonaceous materials that includes introducing a first source of carbonaceous material as a first feedstock into a mixer. Then, a second source of carbonaceous material is introduced as a second feedstock into the mixer. The second feedstock is one of the outputs of the processing of the carbonaceous materials. These carbonaceous materials are mixed into a single feedstock of carbonaceous materials that is customized into a predetermined material composition, and this predetermined mixture is then pyrolyzed in a pyrolyzer to produce a custom carbonaceous output. Other embodiments are also disclosed.