Plastic Comb Binding Plastic comb binding is a popular and cost effective binding method. The pages of comb-bound books lie flat for easy reading. Comb binds are made up of lightweight plastic and can be used for documents up to 7cm thick. The flexible plastic binding can be reopened and closed for additional insertion or deletion of pages and are available in an assortment of colours. Plastic comb binding can bind documents between 5 and 300 pages.