Anti-short bushings are made of polyethylene (plastic) and are designed to comply with CSA and UL requirements. Electricians use roto-splits to cut cable so there is a cleaner cut.
Anti-short bushings used to be made out of fiber. They also used to cut the cable with a hacksaw. Take a look at this old diagram of how the fiber bushings used to look by clicking here. Notice how the guy in the diagram is using a hacksaw to cut the cable, while using his knee to hold the cable taut. Leave your comments on this post if you have any specialized ways of cutting the cable.
