Film-Carrying Bandoliers
Styled after the belts with loops for carrying small arms ammunition and other tools, camera strap bandoliers (sometimes bandoleers) with elastic loops for 35mm film canisters were once common on camera straps, photographers field vests, and inside camera bags.
The bandoliers were also sold as add-ons to existing straps and held to the strap with snap fasteners. Due to the shift to digital cameras theyre not available except used, or possibly, as old, unsold stock.
You can make your own by purchasing the elastic fabric bands from a sewing materials supplier like Jo-Ann Fabrics and sewing the banding into loops attached to a camera strap or wherever they're wanted.