Eating plastic can stem from a wide variety of causes including lack of fiber or other nutritional deficiency. A visit to your veterinarian can rule out medical and dental issues and provide an opportunity to discuss nutrition. Food rotation involves mixing up different cat food brands and flavors which might be recommended. Boredom can also be a factor. Adding enrichment such as daily play sessions, toys, tunnels, scratchers, cat trees and perches can help create a stimulating environment. Keep plastic items away since swallowing plastic pieces can be dangerous. If your cat likes to chew, provide acceptable alternatives such as cat grass, celery or chew toys.