From Longman Dictionary of Contemporary Englishcardboard cut-outˌcardboard ˈcut-out noun [countable] 1 Da picture drawn on cardboard so that it can stand up on a surface2 REAL/NOT IMAGINARYa person or character in a book, film etc who does not seem natural or real the sort of movie in which the characters are just cardboard cut-outs
Examples from the Corpus
cardboard cut-out• A further trick of the light throws their roller-coaster ridge into sharp relief, like a cardboard cut-out.• I also have a life-size cardboard cut-out of our former no.4. 