photographic film , paper , etc . in sheet form is packaged in recyclable containers or cases for reuse by returning to suppliers for filling . containers obviate disposal problems and high costs associated with customary two - part set - up box and interior padding . plastic cases comprise a base section in the form of a tray - like structure with an open bed for a film stack , etc . case has built - in structural features for rigidity , crush resistance , impact protection , and air , dust and light tight seal when used with a cover section . such environmentally friendly designs are suitable as low cost , reusable one - size plastic containers for packaging standard size sheet products . for packaging special , less frequently called - for size films , papers , etc ., interiors may be made infinitely adjustable with rows of parallel channels for placement of at least one chocking element .