Summarythis is version of my shred 5 sq but i have made the cutters so that they accommodate metal cutter inserts. this should be able to cut harder material then. i also changed the handle so that you dont need a separate spacer. the inserts could be made from rectangular metal of some kind. hardened metal or cold rolled whatever. may even be able to fit those carbide inserts. i changed the box to make it deeper to keep stuff from falling out so easy.