Celluloid collars provided a low maintenance, waterproof, alternative to starched linen collars, and were stronger than paper ones. Their high point seems to have been in the 1880s when they were new, but they still regularly sold through the 1920s. Celluloid collars are given to cracking, especially after they age, so this one can’t be flattened and scanned for a pattern. However, you can use a bleach bottle and a pattern from a linen collar to make a replica that is stronger than celluloid, washable, and cheap.
Students from the DVC Beginning Costume Design Class Sp2018 make plastic collars using bleach bottles:
